Răspuns :
{9p+3l=63
{3p+4l=30 |×(-3)
{9p+3l=63
{-9p-12l=-90
9p-9p+3l-12l=63-90
0-9l=-27
-9l=-27 |:(-9)
l=3
3p+4l=30
3p+4×3=30
3p+12=30
3p=30-12
3p=18
p=18:3
p=6
5l=5×3=15
{3p+4l=30 |×(-3)
{9p+3l=63
{-9p-12l=-90
9p-9p+3l-12l=63-90
0-9l=-27
-9l=-27 |:(-9)
l=3
3p+4l=30
3p+4×3=30
3p+12=30
3p=30-12
3p=18
p=18:3
p=6
5l=5×3=15
9p+3l=63 I :3 si le scad
3p+ l = 21
3p+4l=30
--------------------
/ 3l=9
l=3
5l=5x3=15 kg
3p+ l = 21
3p+4l=30
--------------------
/ 3l=9
l=3
5l=5x3=15 kg