F increased by 10% to become 15 % of total ( 3276000 x15 /100 = 491400 )
so in 2017 it was =491400/1.1=446727 approx
B increased by 12% to become 20 % of total ( 3276000 x20 /100 = 655200 )
so in 2017 it was =655200/1.12=585000
so ratio of F and B in 2017 = 446727/585000= 0.7636 (approx)
option A 42/55 =0.7636 is correct ans