Lily has a job doing yard work. she is paid $12 per hour and gets paid $15 bonus when she finishes a yard. write an expression to represent her pay for completing one yard.

T = 12h + 15

t stands for total
h stands for hours

So we don't know how many hours Lily takes to finish a yard. Let's call this number "x". We know that she gets paid 12 per hour-so, for every hour, she would be paid 12 times x hours (or 12x). She then gets paid a $15 bonus for every yard, and this doesn't change. 

So your expression should be y=12x+15. y represents her total pay per yard.