Answer:
2.5
Step-by-step explanation:
Let x be the number of hours both people baby sit and y be the number of hours that they each earn.
Sarah:
y = 10 + 2.5x
Carly:
y = 7.5 + 3.5x
You know that the number of hours should be the same (y).
10 + 2.5x = 7.5 + 3.5x
Evaluate and find x.
10 - 7.5 = 3.5x - 2.5x
x = 2.5
