A blackboard has an area of 28 ft2 and a perimeter of 22 ft. What are the dimensions of the board? 2 ft by 11 ft
2 ft by 14 ft
4 ft by 7 ft
7 ft by 7 ft

Step-by-step explanation:

A=LW, L=A/W

P=2(L+W), using L=A/W we get

P=2(A/W+W)

P=2(A+W^2)/W

PW=2A+2W^2

2W^2-PW+2A=0, given A=28 and P=22 we have

2W^2-22W+56=0

2(W^2-11W+28)=0

2(W-7)(W-4)=0

So the dimensions are 4ft by 7ft

C is the right answer

Step-by-step explanation:

i got it right on the quiz