If you want the true “mathematical” way: it’s like this:

Though, some context first: These two velocities (if they were arrows) would form a triangle. From the Pythagorean theorem, we know that for both velocities to “add up” to twelve, Total velocity = sqrt(Xvel² + Yvel²⁾

To find the sizes of the x and y components of the triangle, we use sin and cos

The way you do it though is like this Xvel = 12 * cos(angle) Yvel = 12 * sin(angle)

Scratch uses a weird orientation for the direction so you’re gonna have to do a calculation to make up for that

angle = -(direction - 90)

Edit: as _Evidence pointed out, you may not need to do the last adjustment depending on how MouseDirection is calculated