4).
3.28 dm ^2 + 1037 cm^2 - 0.012m^2 = 3.28 dm^2 + 10.37 dm^2 - 1.2 dm^2 = 12.45 dm^2
5). 2x = 15.8 ==> x = 15.8/2 = 7.9
x/2 = 7.9 / 2 = 3.95
8).
P = 12 dm
l = 1/2 L
A = ?
A = L x l
L + L + 1/2 L + 1/2 L = 12 ==> 3 L = 12 ==> L = 4
l = 4/2 = 2
A = 4x2 = 8
