Question

How to solve 1.2x+1.4y=2.7 and 0.4x-0.3y=0.9 in substitution

Answer 1

x=0.8712, y=1.1818

Explanation:

1.2x+1.4y=2.7 --(1)

0.4x-0.3y=0.9--(2)

1.2x=2.7-1.4y

x=(2.7-1.4y) / 1.2 --(3)

substitute (3) in (2)

`0.4(2.7-1.4y) / 1.2 -0.3y=0.9`

`(1.8 - 0.56y) (1)/(3) - 0.3y = 0.9`

times both sides with 1/3

`(1)/(3) (1.08 - 0.56y( (1)/(3) ) - 0.3y = 0.9)`

1.08-0.3=0.56y+0.1y

0.78=0.66y

y=1.1818

substitute y in (3)

x=2.7-1.4(1.1818) /1.2

x=0.8712