Answer:
A
Step-by-step explanation:
B
we know the thickness is x, so the sides are 3+2x and 4+2x
then we use foil:
(3+2x)(4+2x)=12+6x+8x+4x^2=4x^2+14x+12
we know the area is 15
4x^2+14x+12=15
4x^2+14x-3=0
So it is B
