Answer:
15.
x = 40/9 = 4 4/9
z = 24/5 = 4 4/5
17.
x = 50
y ≈ 11.5
Explanation:
15. Corresponding segments are proportional:
top right side / whole right side = x / 8
5/(5+4) = x/8
x = 8(5/9) = 40/9
x = 4 4/9
__
right side bottom / right side top = z / 6
z = 6(4/5) = 24/5
z = 4 4/5
____
17. The acute angles are complementary:
x = 90 -40 = 50
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From the Pythagorean theorem:
y = √(15² -9.6²) = √132.84
y ≈ 11.5