Question

What is helpful to do when you have to use more than one unknown variable?

Answer 1

Write an equation y(x)

Answer 2

Answer:

We can solve the equation of two unknown variables for one variable in terms of second variable.

Step-by-step explanation:  

We know that, an equation with a variable can be solve easily. But in the case of two unknown variables, we can solve the equation for one variable in terms of second variable. For example:

If we have given an equation with two unknown variable x+y=4, we can solve this equation for variable y in terms of variable x or we can solve this equation for x in terms of y. Which could be written as:  

y=4-x

or

x=4-y.