You are given a vector in the xy plane that has a magnitude of 85.0 units and a y component of -40.0 units

Incomplete.

To find the x-component of the vector, we can use the Pythagorean theorem and trigonometry.

Let's assume that the x-component of the vector is denoted as x.

We know the magnitude of the vector, which is 85.0 units. According to the Pythagorean theorem, the magnitude of a vector in the xy plane can be expressed as:

magnitude = sqrt(x^2 + y^2)

Substituting the given values:

85.0 = sqrt(x^2 + (-40.0)^2)

To solve for x, we need to isolate it on one side of the equation. Squaring both sides of the equation and rearranging, we get:

7225.0 = x^2 + 1600.0

Rearranging further:

x^2 = 7225.0 - 1600.0
x^2 = 5625.0

Taking the square root of both sides, we find:

x = sqrt(5625.0)
x = 75.0

Therefore, the x-component of the vector is 75.0 units.