# Find Value of Given Equation

If 999x + 888y = 1332 and 888x 999y =555, then X^{2 } – y^{2 }equal is

- 8
- 9
- 5
- 7

**Answer: (4) 7**

**Explanation:-**

999X + 888Y = 1332

111(9X + 8Y) = 1332

9X + 8Y = 1332/111

9X + 8Y = 12 …………………(1)

And,

888X + 999Y = 555

111(8X + 9Y) = 111 x 5

8X + 9Y = 5 ………………………(2)

Solve equation (1) & (2)

Y = -3 & X = 4

X^{2} – Y^{2} = 4^{2} – 3^{2}

= 16 – 9 = 7

Hence, the answer is (4) 7