Each member is encouraged to sell @ least 50 reflectors. You sell 17 on Monday and 12 on Tuesday. How many reflectors do you need to sell on Wednesday to meet your goal?
17 + 12 + x =50 solve for x
Subtract 17 and 12 from the left side to isolate x
What you do to one side of an equation you must do to the other.
x= 50 - 17 - 12
Combine like terms a.k.a. do the math
x=21
You need to sell 21 reflectors to meet the goal of 50