For the first expression
15 + 2d
A possible word problem would be this:
A person saves $2 per day of money. Before he started saving, he had $15 dollars set aside. Look for the expression that expresses the total amount of money saved in terms of the number of days passed
The second expression is
200 - 2m
A possible word problem would be this:
The distance from school to the park is 200m. A kid riding a bike is traveling at a speed of 2m/s from the school to the park. Write an expression for the distance remaining between the park and the kid.