Is y=(x+5)/4 a function?

For every value of x you put in, you can only get 1 y value exg if you subsitue 5 for x then then you will get only 4 and only 4 but it is possible to have 5 for x and get 4 and 20 for x and also get 4, one easy way is to use the vertical line test if you graph the equation and you draw a vertical line throught the line, the vertical line should pass through the equation line only once if we manipulate the equation, we would see that is is = y=x/4+5/4 which is a linear equation that is a striaght line and this passes the vertical line test

2160ft^3 i think you could use a formala to you out with this in the future