Question

what is the value of x in the equation 4x+8y=40 when y=0.8

Answer 1

you plug in the y .8 to the 8 that is 6.4

them you subtract 40 by 6.4 that is  33.6

then you divide that by 4 is 8.4

Answer 2

Substitute in 0.8 for y.

$4x+8y=40 \\ \\ 4x + 8(0.8) = 40 \\ \\ 4x + 6.5 = 40 \\ \\ 4x = 40 - 6.4 \\ \\ 4x = 33.6 \\ \\ x = 8.4$

The final result is: x = 8.4.