Răspuns :
P=2l+2L verifica.
90=2l+2×30 90=2×15+2×30
90=2l+60 90=30+60
2l=90-60
2l=30
l=30÷2
l=15
P = 2L + 2l
90 = 2 x 30 + 2l
90 = 60 + 2l
90 - 60 = 2l
2l = 30
l = 30 : 2
l = 15
Verificare: P = 2L + 2l = 2 x 30 + 2 x 15 = 60 +30 = 90
P = 90
90 = 2 x 30 + 2l
90 = 60 + 2l
90 - 60 = 2l
2l = 30
l = 30 : 2
l = 15
Verificare: P = 2L + 2l = 2 x 30 + 2 x 15 = 60 +30 = 90
P = 90