Question

What is the value of y in the equation 6.4x + 2.8y = 44.4, when x = 3?

Answer 1

(6.4)(3)+2.8y=44.4

Simplify:

(6.4)(3)+2.8y=44.4

19.2+2.8y=44.4

2.8y+19.2=44.4

Subtract 19.2 from both sides.

2.8y+19.2−19.2=44.4−19.2

2.8y=25.2

Divide both sides by 2.8.

2.8y/2.8 = 25.2/2.8

y=9

Answer 2

So you've got:

6.4x + 2.8y = 44.4

You want to know the value of (y) when x=3:

6.4 * 3 + 2.8y = 44.4

(6+0.4) * 3 + 2.8y = 44.4

18 + 1.2 + 2.8y = 44.4

19.2 + 2.8y = 44.4

2.8y= 44.4 - 19.2

2.8y = 25.2

y=(25.2)/(2.8)

y=9