What's the value of
z? - 3x + 1
when x = -2 and y = 42

The mean temperature for the first 4 days in january was 7°c. the mean temperature for the first 5 days in january was 5°c. what was the temperature on the 5th day?

With: label the vertices and all the elements needed. find x

If you are trying to move an attached term across the equal sign (=), what operation would you use to move it?