Answer:
Option A
Step-by-step explanation:
angles ABD and DBC are complementary given
angle ABD=50 degrees given
angles ABD and DBC = 90 degrees def. of complementary
angle DBC = 40 degrees algebra (90-50=40)
angles EBF and ABD are vertical angles vertical angles postulate
angle EBF is congruent to angle ABD def. of vertical angles
angle EBF = 50 degrees def. of congruence
angles EBF and ABF are a linear pair def. of linear pair
angles EBF and ABF are supplementary def. of linear pair
angles EBF and ABF = 180 def. of supplementary
angle ABF = 130 degrees algebra (180-50=130)
angles ABF and EBD are vertical angles vertical angles postulate
angles ABF and EBD are congruent def. of vertical angles
angle EBD = 130 degrees def. of congruence
angles CBE + DBC = EBD diagram
angles CBE + DBC = 130 degrees transitive property of congruence
angle ABD = 90 algebra (130-40=90)
B is needed in the process, but the main statement that actually does the justification is A, so option A
![\bf 1050=1020\left[ 1+r\left( \frac{3}{2} \right) \right]\implies \cfrac{1050}{1020}=1+r\left( \frac{3}{2} \right) \implies \cfrac{35}{34}=1+r\left( \frac{3}{2} \right) \\\\\\ \cfrac{35}{34}-1=\cfrac{3}{2}r\implies \cfrac{1}{34}=\cfrac{3}{2}r\implies \cfrac{2\cdot 1}{3\cdot 34}=r\implies \cfrac{1}{51}=r \\\\\\ r\%=100\cdot \cfrac{1}{51}\implies r\approx\stackrel{\%}{1.96078431372549}](https://tex.z-dn.net/?f=%5Cbf%201050%3D1020%5Cleft%5B%201%2Br%5Cleft%28%20%5Cfrac%7B3%7D%7B2%7D%20%5Cright%29%20%5Cright%5D%5Cimplies%20%5Ccfrac%7B1050%7D%7B1020%7D%3D1%2Br%5Cleft%28%20%5Cfrac%7B3%7D%7B2%7D%20%5Cright%29%20%5Cimplies%20%5Ccfrac%7B35%7D%7B34%7D%3D1%2Br%5Cleft%28%20%5Cfrac%7B3%7D%7B2%7D%20%5Cright%29%0A%5C%5C%5C%5C%5C%5C%0A%5Ccfrac%7B35%7D%7B34%7D-1%3D%5Ccfrac%7B3%7D%7B2%7Dr%5Cimplies%20%5Ccfrac%7B1%7D%7B34%7D%3D%5Ccfrac%7B3%7D%7B2%7Dr%5Cimplies%20%5Ccfrac%7B2%5Ccdot%201%7D%7B3%5Ccdot%2034%7D%3Dr%5Cimplies%20%5Ccfrac%7B1%7D%7B51%7D%3Dr%0A%5C%5C%5C%5C%5C%5C%0Ar%5C%25%3D100%5Ccdot%20%5Ccfrac%7B1%7D%7B51%7D%5Cimplies%20r%5Capprox%5Cstackrel%7B%5C%25%7D%7B1.96078431372549%7D)