Answer:
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
