4y=3 over x2 + 2, what is the value of x

This equation has two variables . . . 'x' and 'y' .
It doesn't tell what they are; it only tells you their relationship.
In fact, they can be millions of different numbers, but every pair of
'x' and 'y' are related according to this equation.
You can draw a graph of the equation, and every point on the graph
is a pair of numbers (x, y) that is a solution to the equation.

To find one pair that works, just pick any number for 'x', write it
into the equation in place of 'x', and figure out what 'y' is.  That'll
give you one pair of numbers that are a point on the graph. 
There are an infinite number of others.