This answer is the third choice, C
Eqt 1 = 4a-5b=7
eqt 2 = 4a+5b=17
eqt1+eqt2= 8a=24
a=3 then 4*3-5b=7
so b=1
The two sides and two top angles are identical so the two bottom halves are the same
18 -2r = 4R
Add 2r to both sides
18 = 6r
Divide both sides by 6
R = 3
The answer is A. 3
1 + -3 1/2 is = to -2.5 so v= -2.5