4)
80 cm = 8 dm - lungimea drept.
8 x a = 40
a = 40 : 8 = 5 dm - latimea drept.
P = ( 5+8) x 2 = 13 x2 = 26 dm
5)
daca se imparte in 2 patrate, atunci lungimea = 2 latimi
latimea = x
lungimea = 2x
(x+2x) x2 = 30
3x = 30:2 = 15
x = 15 : 3 = 5
latimea-5
lungimea-10
A=10 x5 =50cm^2
