$(x-8)(y+10)=xy$

$⇒xy-8y+10x-80=xy$

$5x-4y=40$   ...(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 = $xy = 960$

Eq. (1) → $5x-4y=40$

Eq. (2) → $10x-8y=80⇒5x-4y=40$