Cathay had saved $335. she spent $15 each week for guitar lessons. she now has $155. write an equation and solve to find out how many lesson cathay had.

She started out with 335, and spent 15 each week, she now has 155 dollars- that will be our equal sign. 

let m= money she spent each week.

335- 15m= 155

Subtract 335 from 155. 

-15m= -180

Divide -15 into both sides.

m= 12

Cathy had 12 lessons.

I hope this helps!
~kaikers