Question

(C) 10
41. If (3x - y) = (x + 5y) = 5:7, then the
value of (x + y) : (x - y) is:​

Answer 1

In ratios, the numerator of LHS is equal to numerator of RHS and same with the denominators.

Here,

• 3x - y = 5 ----(i) × 1
• x + 5y = 7 ----(ii) × 3

Equation (i) becomes, 3x - y = 5 ----(a)

Equation (ii) becomes, 3x + 15y = 21 ---(b)

Subtracting equation (a) from equation (b), we get,

→ 3x + 15y - (3x - y) = 21 - 5

→ 3x + 15y - 3x + y = 16

→ 16y = 16

→ y = 1

From equation (ii), we have

x = 7 - 5y

x = 7 - 5(1)

x = 7 - 5 = 2

Thus,

$\mapsto \: \tt \frac{x + y}{x - y} \\ \\ \mapsto \: \sf \frac{2 + 1}{2 - 1} = \frac{3}{1}$

Hence,

• (x + y) : (x - y) = 3 : 1