How do you solve to find a linear function? need

When a question asks to solve the linear function it usually means making the equation equal to zero ( =0).

For example: solve -x + 5.

1. we will equal it to zero, so -x + 5 = 0.
2. solve for x, so we rearrange the equation to get the x value. In this case:

- x + 5 = 0 and add x to the other side so..
5 = x

Hope that helps !

Equatorial triangle and obtuce angle