Question

5 mingi si 7 palete costa 117 lei ,iar 3 mingi si 5 palete costa 79 lei aflati cat costa o minge si cat costa o paleta.

Answer 1

Răspuns:

5 mingi..............7 palete...... 117 lei -

3 mingi................5 palete ........ 79 lei

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2m+2p=38=>2(m+p)=38=>m+p=38:2=>m+p=19

m=19-p

5m+7p=117

5(19-p)+7p=117

95-5p+7p=117

2p=117-95

p=22:2=>p=11 lei costa o paleta

m=19-11=>m=8 lei costa o minge

Answer 2

Răspuns:

Notam cu x mingile si cu y paletele

5x+7y=117

3x+5y=79

Prima ecuatie o inmultim cu (-3)

A doua ecuatie inmultim cu 5

Si adunam ecuatiile, astfel se reduc termenii cu x

5*(-3)*x+7*(-3)y+3*5*x+5y*5=117*(-3)+5*79

-15x+(-21)*y+15x+25y=-351+395

-21y+25y=44

4y=44

Y=11

5x+11*7=117

5x+77=117

5x=117-77

5x=40

X=40/5

X=8