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aflati numerele a si b,stiind ca a+6b=135 si 2a+3b=90

Răspuns :

Hatty
a+6b=135
2a+3b=90
3a+9b=225
a+3b=75
a=90-75
a=15
3b=75-15
3b=60
b=20
a+6×b=135
2×a+3×b=90 |×2
______________
a+6×b=135
4×a+6×b=180
______________
4×a-a=180-135
3×a=45
a=45:3
a=15
_____________
15+6×b=135
6×b=135-15
6×b=120
b=120:6
b=20