a b c d

d

$(x-8)(y+10)=xy$ $⇒xy-8y+10x-80=xy$ $5x-4y=40$   ...(1) or $10x-8y=80$  ...(2) $(x+16)(y-10)=xy$ $xy+16y-10x-160=xy$ $8y-5x=80$  ...(3) eq. (3) + eq. (2) We get, $5x=160$ $x=32$ → no. of children putting x in (1) we get, $y = 30$ → money spent on each child so money spent = $xy = 960$