The perimeter of the parallelogram is 40 cm. One of its sides is 7 cm larger than the other. Find the sides of the parallelogram.

the parallelogram has equal parallel sides, so we divide the perimeter by two, and thus find the sum of one and the other side:
40: 2 = 20 (cm)
Since the difference is 7 cm, we will compose and solve the equation:
x + (x + 7) = 20, where x is the length of the smaller of the two sides
2x + 7 = 20
2x = 13
x = 6.5 – first side
6.5 + 7 = 13.5 – second side