Answer: 3
Step-by-step explanation: Okay the question mark is a variable, you are trying to figure out what number is the question mark to do this you...
First find out what 3(28) + 3(2) is and that should be 90.
You are basically using this formula yes, you might not understand but I will give you your answer.
90 = 30x
You divide 90 by 30 and get 3 as the question mark or x.