Answer :
you can do 9/1 x A
2 x (9/0.5 x B)
9/0.25 x C
so 9A + 36B + 36C
(9 x 50) + (36 x 80) + (36 x 120) = 450 + 2880 + 4320 = $7650
2 x (9/0.5 x B)
9/0.25 x C
so 9A + 36B + 36C
(9 x 50) + (36 x 80) + (36 x 120) = 450 + 2880 + 4320 = $7650