Question

find (x+y),if 3x+5y=18;5x+3y=22​

Answer 1

Answer : (x + y) = 5

Explanation :

we have given ,

3x + 5y = 18 ------(1)

5x + 3y = 22-------(2)

multiply equation (1) by 5 and equation (2) by 3

we get,

15x + 25y = 90 ------(3)

15x + 9y = 66 ----(4)

subtract equation (4) from equation (3) ,

15x + 25y = 90

15x + 9y = 66

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_______________

16y = 24

y = 24 /16

y = 3 / 2

put the value of y in equation (1) we get,

3x + 5y = 18

3x + 5(3/2) = 18

3x + (15/2) = 18

6x + 15 = 36

x = (36 - 15)/6

x = 21 /6

x = 7 / 2

(x + y) = (3/2) + (7/2)

= 10 / 2 = 5

therefore the value of (x + y) is 5