there is no specific formula for questions like these. you have to solve these questions by secluding the variable.

The first one would be done this way:

subtract 4x from both sides:

so,

now divide both sides by 3, because you have to find out what x is:

this gives you:

So the value of x is 3.

Can you try doing the same for your second problem. Give it a shot and reply back if you have problems!