m<1 = m<4 by vertical angles theorem
3x + 10 = 4x - 15
-1x = -25
x = 25
m<1 + m<7 = 180 if parallel alternate interior angles supplementary
3x + 10 + m<7 = 180
3(25) + 10 + m<7 = 180
75 + m<7 = 180
m<7 = 105°
Hope this helps! ;)
