Answer:
5 carwashes, Josh: $ 100 savings, Sandra: $100 savings
Step-by-step explanation:
First we need to find each of their formulas.
Formula for Josh: 50+10c=s
Formula for Sandra:25+15c=s
We can set these two to be equal to each other in order to find how many carwashes it takes for them to have the same amount of money.
50+10c=25+15c
25+10c=15c
25=5c
c=5
after 5 car washes, they will have the same amount of money.
now that we know that, we can plug that into each equation to find each of their savings after the 5 carwashes.
Josh's savings:
50+10c=s
plug in the amount of carwashes,
50+10*5=s
50+50=s
s=100 dollars of savings for Josh
Sandra's savings:
25+15c=s
plug in the amount of carwashes,
25+15*5=s
25+75=s
s=100 dollars of savings for Sandra
