Answer:
Perimeter is 80cm
Step-by-step explanation:
A rectangle's area is calculated by multiplying the length by the width. If we are given the area of the rectangle and the length then we would simply need to solve for the width of the rectangle using the area formula we just mentioned...
A = l * w
336 = 12cm * w ... divide both sides by 12cm
28cm = w
Now we can see that the width of this rectangle is 28cm. To find the perimeter we need to add all four sides together, since we know that a rectangle's opposite sides are the same then we add the length and the width twice to calculate the perimeter (P)
P = 12cm + 12cm + 28cm + 28cm
P = 80cm