Answer:
10 inches by 4 inches
Step-by-step explanation:
Area of envelope, A = 40 in²
Perimeter of envelope, P = 28 in
Area = Length * width, L*W
Perimeter = 2(L + W)
40 = LW - - - (1)
28 = 2(L+W)
28/2 = L+W
14 = L+W - - - (2)
Solving like a quadratic equation ;
We need two numbers whose sum gives 14 and product gives 40
The numbers are 10 and 4
(10*4) = 40 and (10+4) = 14
