Question

3 frezi si 5 trandafiri costa 31 de lei
7 frezi si 5 tranafiri costa 39 lei
Cat costa 1 frezie ?
Dar 1 trandafir ?

Answer 1

3F+5T=31
7F+5T=39  =>4F+3F+5T=39
4F+31=39
4F=39-31
4F=8  =>F=8:4=2
3X2+5T=31
6+5T=31
5T=31-6
5T=25  =>T=25:5
T=5

Answer 2

x= frezii
y =trand

3x+5y =31
7x+5y =39  I -
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4x   /   =8
x =2 lei
3*2 +5y =31
6+5y =31
5y =31-6 =25
y =5 lei