Question

if 3x+y=9 and 5x+3y=7 then what is value of x+y
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Answer 1

Answer:

3x+y = 9

y = 9-3x

5x+3y = 7

5x = 7-3y

x = 7-3y/5

x = 7-3(9-3x) /5

x = 7-27+9x/5

x = -20+9x/5

x*5= -20+9x

5x -9x = -20

-4x = -20

x = -20/-4

x = 5

y = 9-3(5)

y = 9-15

y = -6

x+y = 5+(-6)

x+y = -1