Explain how to comapre two lengths that are mesurered in different- sized units

3 feet = 36 inches or 1 yard

You can write an equation in 2 variables to slove a problem by Solving  for y  using  The Method of Elimination: The process of substitution involves several steps: In a two-variable problem rewrite the equations so that when the equations are added, one of the variables is eliminated, and then solve for the remaining variable.