Answer:
m<B = 58 degrees, m<C = 63 degrees
Explanation:
let's find y!
angles B and A are complementary, so they should equal 90
therefore, B + A = 90
substitute
4y + 8y - 6 =90
12y = 96
y=8, and m<B = 8y-6; so m<B = 58
angles C and D are equal because of vertical angles
therefore, C = D
substitute
7x=5x+18
2x=18
x=9
m<C = 7x, so m<C = 63