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
