Help!! I find this a bit difficult, any help would work :(

Add the two expressions 3.8b - 7 and 2.9b + 9 enter your answer in simplified form

Which of the following contains a variable?

Miss henderson wants to build a fence around a rectangular garden in her backyard in the scale drawing the perimeter of the garden is 14 in of the actual length of a b is 20 ft how many feet of fencing what you need