Cara put $18 into her savings account last week. This is 90% of the amount she earned baby sitting. What amount did she earn baby sitting?

Question

Cara put $18 into her savings account last week. This is 90% of the amount she earned babysitting. What amount did she earn baby sitting? 

Answer 1

Here's what we know:

.9x = 18 (90% = 0.9, and 0.9 of an unknown number is $18)

 

Divide both sides by .9:

.9x / .9 = 18 / .9

x = 20

 

So Cara made $20 from babysitting.