(a) Ivanna is saving money to buy a bike that costs $125 . She has $60 and will save an additional $5 each week. In how many weeks will she have enough money to buy the bike? Write an equation that could be used to answer the question above. First, choose the appropriate form. Then, fill in the blanks with the numbers 125 , 60, and 5. Let w represent the number of weeks.

o_w+_=_
o_w-_=_

(b) Solve the equation in part (a) to find the number of weeks.
w=_