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diff --git a/crates/typst-library/src/math/cancel.rs b/crates/typst-library/src/math/cancel.rs
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+++ b/crates/typst-library/src/math/cancel.rs
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+use crate::foundations::{cast, elem, Content, Func, Smart};
+use crate::layout::{Abs, Angle, Length, Ratio, Rel};
+use crate::math::Mathy;
+use crate::visualize::Stroke;
+
+/// Displays a diagonal line over a part of an equation.
+///
+/// This is commonly used to show the elimination of a term.
+///
+/// # Example
+/// ```example
+/// >>> #set page(width: 140pt)
+/// Here, we can simplify:
+/// $ (a dot b dot cancel(x)) /
+///     cancel(x) $
+/// ```
+#[elem(Mathy)]
+pub struct CancelElem {
+    /// The content over which the line should be placed.
+    #[required]
+    pub body: Content,
+
+    /// The length of the line, relative to the length of the diagonal spanning
+    /// the whole element being "cancelled". A value of `{100%}` would then have
+    /// the line span precisely the element's diagonal.
+    ///
+    /// ```example
+    /// >>> #set page(width: 140pt)
+    /// $ a + cancel(x, length: #200%)
+    ///     - cancel(x, length: #200%) $
+    /// ```
+    #[default(Rel::new(Ratio::one(), Abs::pt(3.0).into()))]
+    pub length: Rel<Length>,
+
+    /// Whether the cancel line should be inverted (flipped along the y-axis).
+    /// For the default angle setting, inverted means the cancel line
+    /// points to the top left instead of top right.
+    ///
+    /// ```example
+    /// >>> #set page(width: 140pt)
+    /// $ (a cancel((b + c), inverted: #true)) /
+    ///     cancel(b + c, inverted: #true) $
+    /// ```
+    #[default(false)]
+    pub inverted: bool,
+
+    /// Whether two opposing cancel lines should be drawn, forming a cross over
+    /// the element. Overrides `inverted`.
+    ///
+    /// ```example
+    /// >>> #set page(width: 140pt)
+    /// $ cancel(Pi, cross: #true) $
+    /// ```
+    #[default(false)]
+    pub cross: bool,
+
+    /// How much to rotate the cancel line.
+    ///
+    /// - If given an angle, the line is rotated by that angle clockwise with
+    ///   respect to the y-axis.
+    /// - If `{auto}`, the line assumes the default angle; that is, along the
+    ///   rising diagonal of the content box.
+    /// - If given a function `angle => angle`, the line is rotated, with
+    ///   respect to the y-axis, by the angle returned by that function. The
+    ///   function receives the default angle as its input.
+    ///
+    /// ```example
+    /// >>> #set page(width: 140pt)
+    /// $ cancel(Pi)
+    ///   cancel(Pi, angle: #0deg)
+    ///   cancel(Pi, angle: #45deg)
+    ///   cancel(Pi, angle: #90deg)
+    ///   cancel(1/(1+x), angle: #(a => a + 45deg))
+    ///   cancel(1/(1+x), angle: #(a => a + 90deg)) $
+    /// ```
+    pub angle: Smart<CancelAngle>,
+
+    /// How to [stroke]($stroke) the cancel line.
+    ///
+    /// ```example
+    /// >>> #set page(width: 140pt)
+    /// $ cancel(
+    ///   sum x,
+    ///   stroke: #(
+    ///     paint: red,
+    ///     thickness: 1.5pt,
+    ///     dash: "dashed",
+    ///   ),
+    /// ) $
+    /// ```
+    #[resolve]
+    #[fold]
+    #[default(Stroke {
+        // Default stroke has 0.5pt for better visuals.
+        thickness: Smart::Custom(Abs::pt(0.5).into()),
+        ..Default::default()
+    })]
+    pub stroke: Stroke,
+}
+
+/// Defines the cancel line.
+#[derive(Debug, Clone, PartialEq, Hash)]
+pub enum CancelAngle {
+    Angle(Angle),
+    Func(Func),
+}
+
+cast! {
+    CancelAngle,
+    self => match self {
+        Self::Angle(v) => v.into_value(),
+        Self::Func(v) => v.into_value()
+    },
+    v: Angle => CancelAngle::Angle(v),
+    v: Func => CancelAngle::Func(v),
+}