Kristy makes 5$ per hour babysitting and 12$ per hour giving music lessons. One weekend, she worked a total of 18 hours and made $139.00. How many hours did she spend babysitting? Write your answer in complete sentences.

Let Karen works x hours baby sitting

So, she worked (18-x) hours giving music lessons

So,

According to question

5x + 12 (18-x) = 139

This gives

7*x=77

x=11

So,

Karen worked 11 hours baby sitting and (18-11) = 7 hours giving music lessons