# How do you solve -2.5x + 1.4y = -10.2 and 1.2x - 4.5y = -21.9?

Apr 25, 2018

Solution: $x = 8 , y = 7$

#### Explanation:

 -2.5 x +1.4 y = -10.2 (1) ; 1.2 x -4.5 y = -21.9 (2)

Multiplying by $10$ on both sides of the equations (1) and (2) we

get,  -25 x +14 y = -102 (3) ; 12 x -45 y = -219 (4)

Multiplying by $12$ on both sides of the equation (3) we get,

$- 300 x + 168 y = - 1224 \left(5\right)$

Multiplying by $25$ on both sides of the equation (4) we get,

$300 x - 1125 y = - 5475 \left(6\right)$ Adding equations (5) and (6)

we get, $- 957 y = - 6699 \therefore y = \frac{- 6699}{-} 957 = 7$ Putting

$y = 7$ in equation (3) we get $- 25 x + 14 \cdot 7 = - 102$ or

$- 25 x = - 102 - 98 \mathmr{and} - 25 x = - 200 \mathmr{and} x = \frac{- 200}{-} 25 = 8$

Solution: $x = 8 , y = 7$ [Ans]