Let x = cost of the dishwasher.
The amounts the children are paying are:
Mark =20% = 1/5, so 1/5x
Sorin = 75
Raymond = 1/4x
Stephanie = 75
Kristin = 1/3x
Add them together:
x = 1/5x + 1/4x + 1/3x + 75 + 75
x - ( 1/5x + 1/4x + 1/3x ) = 150
Rewrite fractions with common denominator:
x - ( 12/60x + 15/60x + 20/60x ) = 150
60/60x - 47/60x = 150
13/60x = 150
x = 150/1 • 60/13
x = 9000/13
x = 692.31
The total cost of the dishwasher is $692.31
Now calculate the amount each child pays:
Mark = 1/5 x = 692.31/ 5 = $138.46
Sorin = $75.00
Raymond = 1/4 x = 692.31 / 4 = $173.08
Stephanie = $75.00
Kristin = 1/3 x = 692.31 / 3 = $230.77