If -26+z=15 what is the value of z?

To find the value of z, you need to isolate it on one side of the equation.

-26 + z = 15

To isolate z, you want to get rid of the -26 on the left side of the equation. To do this, you can add 26 to both sides of the equation to cancel out the -26:

-26 + 26 + z = 15 + 26
z = 41

Therefore, the value of z is 41.