Question 1182223
Let  each boy pay  x
and number of boys be y

there had been 3 boys fewer, each would have paid one dollar more

(y-3)(x+1) = xy
xy+y-3x -3 =xy

y-3x=3
y=3x+3----------------(1)

(y+4)(x-3/4) = xy

xy -(3/4)y +4x -3 =xy

-3/4 y +4x = 3
multiply by 4

-3y +16x =12--------------(2)
substitute y in (2)
-3(3x+3)+16x =12

-9x-9 +16x =12
7x =21
x= 3

y=3x+3
y= 3*3 +3

y=12

Cost of Ball = 4*12 =48

$48