Calculate the perimeter of a quadrilateral if the length of one side is 16 cm

Calculate the perimeter of a quadrilateral if the length of one side is 16 cm, the other side is 4 cm longer, and the sum of the lengths of the two remaining sides is 45 cm.

First you need to figure out what a perimeter is. In this case, P (perimeter) is the sum of all sides, so to find the sum of all sides, you need to know the length of each side.
Let us denote in literal terms all sides of the quadrilateral. P = a + b + c + d
a – the first side, equal to 16 cm
b – the second side, it is more than a by 4 cm. b = 16 + 4 = 20 cm
d and c – the third and fourth sides, their sum is 45 cm
We have all the values, we substitute them into the formula and calculate
16 + 20 + 45 = 81cm
Answer; perimeter is 81 cm