Eqn 1

0.3x + 0.2y = 5

0.2y = 5 - 0.3x

0.4y = 10 - 0.6x

Eqn 2

0.5x + 0.4y = 11

0.4y = 11 - 0.5x

10 - 0.6x = 11 - 0.5x Substitute Eqn in to eqn 2

10 - 11 = -0.5x + 0.6x rearrange

-1 = 0.1x

-10 = x x = -10

0.4y = 11 - 0.5(-10) = 11 + 5 = 16

0.4y = 16

(10/4)(4/10)y = y = (10/4)(16) = 40

checking:

x = -10, y = 40

0.5(-10) + 0.4(40) = -5 + 16 = 11 Correct!