Question

What is the value of x in the equation 4x + 8y = 40, when y = 0.8?

4.6
8.4
10
12

Answer 1

y           x
0.8      8.4
4.6      0.8
8.4     -6.8
10     -10
12     -14

Answer 2

4x + 8y = 40

When y = 0,8 :

4x + 8*0,8 = 40
4x + 6,4 = 40
4x = 40 - 6,4
4x = 33,6
x = 33,6/4
x = 8,4

Answer : 8,4