Question

5x + 6y = 13 7x + 5y =8

Answer 1

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$\longrightarrow \: \rm \: 5x + 6y = 13 ....(i)\\ \\\longrightarrow \: \rm \: 7x + 5y = 8....(ii)$

Multiply eq(i) by 7 and eq(ii) by 5

$\longrightarrow \: \rm35x + 42y = 91....(iii) \\ \\ \longrightarrow \: \rm35x + 25y = 40....(iv)$

now ,

Subtract eq(ii) from eq(i)

$\implies \rm\: 35x + 42y - (35x + 25y) = 91 - 40$

$\implies \: \rm \: 17y = 51 \\ \\\implies \: \rm \: y = 3$

Put the value of y in eq(i)

$\implies \rm\: 5x + 6(3) = 8 \\ \\ \implies \rm \: \: 5x + 18 = 8 \\ \\ \implies \: \rm \: 5x = - 10 \\ \\ \implies \: \rm \: x = - 2$

Answer 2

Step-by-step explanation:

5x+13=7x+5y-6y=8

5x+13=7x+y=8

13=5x-7x+y=8

13=2x+y=8

13=2xy=8

2xy=8-13

2xy=5

2xy=5

xy=2-5

therefore=xy=3