A has to pay £51 (and B pays £34) This is how you work it out: A:B 3:2 3+2=5, 85/5 = 17 (this is what you would have to pay if your part of the ratio was 1) therefore, to find what A pays, you times the part 1 by 3 (as the ratio is 3:2) 17 x 3 = 51 (likewise, 17x2= 34 which is what B has to pay)
