Ineed . i don't know how to do this. y/20=x. i need to know what x is for the problem.

also i need with this problem. y+1/7x=1/2

explain

Given Y/20=X, you can not go further until you know the value of Y.

So, just write X=Y/20.

If Y=100, X=5.

Regarding the 2nd problem:  You have not provided instructions:  Y+1/7x=1/2

If you wish to solve for Y, subtract (1/7)x from both sides of this equation.  Ideally you'd find the LCD of (1/2) and (1/7) and write the right side of the resulting equation in the form -ax + b
                                               
                                                    14.