Question

Can you help me please

Answer 1

In this case we know a and b are parallels, and the angle show on the bottom is 90 degrees so 4x-18 has to be equal 90 too:

4x+18=90

4x=90-18

x=72/4

x=18

If a and b are parallels, then 4x+18 has to be equal to 90