Find the sides of the rectangle if its area is 56 cm2 and the perimeter is 30 cm.

1) we start with the area, it is equal to S = ab, substitute and get 56 = ab
2) perimeter 2 (a + b) = P, substitute the perimeter into the formula and get (a + b) 2 = 30, divide by 2 and get a + b = 15, express and get a = 15-b
3) put in the area formula b (15-b) = 56, 15b-b ^ 2 = 56, solving this quadratic equation we get b = 7, a = 8
Answer: 7; 8