Let 'a' be the length of one side
'b' be the length of the other side
P = 2a + 2b
Perimeter is 80cm
80 = 2a + 2b
Divide the whole equation with 2
40 = a + b ----equation 1
From the statement 'if one side is 8cm more than the other side'
b = a + 8 ----equation 2
Substitute equation 2 to equation 1
40 = a + b
40 = a + a + 8
40 - 8 = a + a
32 = 2a
a = 32/2
a = 16 cm
Substitute a=16 to equation 2
b = a + 8
b = 16 + 8
b = 24 cm
Therefore the sides of the parallelogram measures 16 cm by 24 cm
