The measure of 1 is also 78 because 1 and 5 are corresponding angles.
This should be it. Hope that helps!
If 5 is the base, 3(x-1) is the argument:
3x-1=5²
3x=26
x=26/3
If 5 is with 3x-1, that is, if 5(3x-1) is the argument, and the base is 10:
5(3x-1)=10²
3x-1=20
3x=21
x=7
