Question

Solve 0.4x + 0.3y =1.7 ; 0.7x +0.2y = 0.8 by elimination method

Answer 1

Answer:

x = $\frac{-10}{13}$

y = $\frac{87}{13}$

Step-by-step explanation:

0.4x + 0.3y = 1.7            (Given)

10(0.4x + 0.3y) = 10(1.7)

∴ 4x + 3y = 17                ( 1 ) × 2

0.7x + 0.2y = 0.8            (Given)

10(0.7x + 0.2y) = 10(1.7)

∴ 7x + 2y = 8                ( 2 ) × 3

Subtracting ( 1 ) & ( 2 ):

  8x + 6y =   34

- 21x - 6y = - 24

____________

- 13x = 10

∴ x = $\frac{-10}{13}$

Substituting in (1):

4 × $\frac{-10}{13}$ + 3y = 17

$\frac{-40}{13}$  + 3y = 17

3y = 17 + $\frac{40}{13}$

3y = $\frac{221 + 40}{13}$

3y = $\frac{261}{13}$

y = $\frac{261}{39}$

y = $\frac{87}{13}$