Answer:
The equation 2d + 18 = 24 can help find the number of days Jerry has been doing sit-ups.
Explanation:
During the first day, Jerry did 18 sit-ups, and he proceeded to do 2 more sit-ups each following day, so the expression to represent this situation is 2d + 18. Because he did 24 sit-ups today, to find the number of days he did sit-ups, the equation to solve is 2d + 18 = 24.