We know the width of the rectangle in the middle of the trapezoid is 24 (from the top of the image), so we can subtract that from the bottom width of the trapezoid to get the combined length of the bottom of both triangles.

Since this is an isosceles trapezoid, both triangle bases are the same length, so we can cut this value in half to get the length of
and 

Finally, we can use the Pythagorean Theorem to find the length of
:





Answer:
12 in.
Step-by-step explanation:
Formula: a^2 + b^2 = c^2
This case: c^2 - a^2 = b^2
1) 15^2 + 9^2 = b^2
2) 225 - 81 = 144
3)
= 12
1-5/8=3/8
If he had 5/8 leftover, then he used 3/8.
(311&1/4-186&3/4)/(5-3)=62&1/4
so the difference between each adjacent number is 62&1/4
when the top number is 4, the bottom number is 186&3/4+62&1/4=249 (a)
when the top number is 4, the bottom number is 311&1/4+62&1/4=373&1/2 (b)
C=10