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daca ab+2ac=35 si 10b+20c=50 afla nr a

Răspuns :

ab+2ac=35 si 10b+20c=50
a(b+2c)=35 si 10(b+2c)=50⇔b+2c=50÷10=5
inlocuim b+2c in prima ecuatie
ax5=35
a=35÷5
a=7

10b+20c=50 |:10
b + 2c = 5

ab + 2 ac = 35
a ×(b + 2c) = 35
inlocuim b+2c cu 5
a × 5 = 35
a = 35 : 5
a = 7