Question

if 3 x+5y=9and5x+3y=7then what is the value of x+y?​

Answer 1

Adding both the equations,

3x+5y=9

+ 5x+3y=7

_________

8x+8y=16

Therefore,

8(x+y)=16

x+y =16/8

x+y=2

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Answer 2

Answer:

x + y = 4

Explanation:

3x + 5y = 9 ------------(1)

5x + 3y = 7 ------------(2)

Multiplying eq.(1) by 5 and eq.(2) by 3

5×(3x + 5y = 9)

3×(5x + 3y = 7)

15x + 25y = 45 -----------(3)

15x + 9y = 21 ------------(4)

Now, subtract eq. 3 and eq.4

15x + 25y = 45

15x + 9y = 21

(-) (-) (-)

___________

16y = 24

y = 24/16

y = 3/2

Now, putting the value of y in eq. 1

3x + 5 × 3/2 = 9

3x = 9 - 15/2

3x = (18 -15)/2

3x = 3/2

x = 1/2

Now , x+y => 1/2 + 3/2 = 4/2 = 2

Therefore, x + y = 4

Hope you understand it

Thank you