find the value of y when x = 8

Aren't you missing something in this problem? As you state it, it's not solvable.

Sorry, solve 3x+4y=8 for y and then using your answer find the corresponding value of y when x=8

3x+4y=8

3 * 8 + 4y = 8
24 + 4y = 8
4y = -16
y = -4

Proof:

24 - 16 = 8

3x+4y=8

3*8+4y=8
24+4y=8
4y= -16
y=-4
Proof 24-16=8

To find the value of y when x = 8, we would need more information. The relationship between x and y must be defined in some way, such as in an equation, a graph, or a table of values. Without this information, it is not possible to determine the value of y when x = 8.

If you have an equation that relates x and y, you can substitute x = 8 into the equation and solve for y. For example, if you have the equation y = 2x + 3, you can substitute x = 8 into the equation:

y = 2(8) + 3
y = 16 + 3
y = 19

In this case, when x = 8, y would equal 19.

If you have a graph or a table of values, you can locate the point on the graph or in the table where x = 8 and find the corresponding value of y.

If you provide more information or context about the relationship between x and y, I can assist you further in finding the value of y when x = 8.