Joe earned money for baby-sitting, he spent 1/4 of the money on a guitar then he gave 1/4 to charity, if he has $108 left how much money did he start with?

216 US dollars

Step-by-step explanation:

Let the amount he earned for babysitting be x

He spent 1/4 of x on guitar = (1/4) * x=1/4x

He gave 1/4 of x to charity = (1/4) * x=1/4x

Equation 1

Total amount left = (Total amount earned - Total amount spent)

Total amount earned=x

Total amount spent = (Spent on Guitar+Spent on Charity) = (1/4x) + (1/4x) = 1/2x=0.5x

Total amount left=108 US dollars

Substituting in equation 1

108 = (x-0,5x)

Solving

0.5x/0.5=108/0.5

x=216 US dollars

He started with 216 US dollars