Verified Answer :

konrad509

\(5\cdot20-2\cdot15=70\\ 100-30=70\\ 70=70\leftarrow \text{ true}\\\\ 3\cdot20+4\cdot15=120\\ 60+60=120\\ 120=120\leftarrow \text{ true}\)

eu99li

{5x-2y=70    /2

{3x+4y=120

___________________

{10x-4y=140

{3x+4y=120        (+)

13x=260   /:13

x=20

3x+4y=120

320+4y=120

4y=120-60

4y=60   /:4

y=15

So the solution is (20; 15)

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