Question

If 12x+17y=11 and 7x-8y=4 , then what is rhe value of x+y?​

Answer 1

Answer: 37/43

Given pair of linear equation in two variables is:

• 12x + 17y = 11 ...(i)
• 7x - 8y = 4 ...(ii)

For simplicity we will solve this pair of linear equation by adding or subtracting and not by some complex methods like cross-multiplication, elimination, e.t.c

At first, We can see that the coefficient of either variables of both the linear equations ain't same. so let's make the coefficient of variable x same in both equations.

Multiply eq.(i) by 7 and eq.(ii) by 12, In this way the coefficient of x will be same which is 84.

⇒ 84x + 119y = 77 ...(iii)

⇒ 84x - 96y = 48 ...(iv)

Subtract (iv) from (iii), we get

⇒ 84x + 119y - (84x - 96y) = 77 - 48

⇒ 84x + 119y - 84x + 96y = 29

⇒ 215y = 29

⇒ y = 29/215

Substitute ( y = 29/215 ) in (iii)

⇒ 84x + 119 × 29/215 = 77

⇒ 84x + 3451/215 = 77

⇒ 84x = 77 - 3451/215

⇒ 84x = 13104/215

⇒ x = 156/215

Now, We have to find the value of (x + y):

⇒ x + y

⇒ 156/215 + 29/215

⇒ (156 + 29) / 215

⇒ 185 / 215

⇒ 37 / 43

Hence, The value of x + y is 37/43

Answer 2

Answer:

The value of x+y is 37/43.

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