Answer:
When x = 8.4 and y = .8 then 4x + 8y = 40
Explanation:
4x + 8y = 40
y = .8
Let's solve for x by substituting .8 for y (since y is given)
4x + 8(.8) = 40
4x + 6.4 = 40 Subtract 6.4 from both sides.
4x + 6.4 - 6.4 = 40 - 6.4
4x = 33.6 Divide each side by 4
4x/4 = 33.6/4 4 cancels on the left because 4/4 = 1
x = 33.6/4
x = 8.4
So when x = 8.4 and y = .8 then 4x + 8y = 40