Find the equation that represents the proportional relationship between in this graph

the third one!

Step-by-step explanation:

Because it says, the SUM of the number, x (or z I can't really see it well) and 1/2, you must add those two together:

1/2 + x

Then it says those two numbers equal to 4, so it would look like this:

1/2 + x = 4

Because you are trying to isolate, and solve for x, you must SUBTRACT 1/2 from both sides of the equal sign:

1/2  +  x  =  4

-1/2            -1/2

1/2 minus 1/2 would result 0, so there would be x by itself. and 4 minus 1/2 would be 3 and a half ( 3  1/2), so x would be  3  1/2

x = 3 1/2

Hope this helped. If this is incorrect please specify so I can help :)