Question

Jerry started doing sit-ups every day. The first day he did 15 sit-ups. Every day after that he did 2 more sit-ups than he had done the previous day. Today Jerry did 28 sit-ups. Write an equation that could be solved to find the number of days Jerry has been doing sit-ups since the first day.

Answer 1

y = sit ups, x= days

y= 2x + 15
33 = 2x + 15 (subtract 15 from both sides)
18 = 2x (divide both sides by 2)
9 = x, 9 days

Answer 2

y=2x+15
where y=number of sit ups
x=number of days