Question

The three Math Idol judges have been eliminating contestants all day! The number of one-step equations and two-step equations who have been eliminated today is equal to 1070! If three times the number of one-step equations minus twice the number of two-step equations is equal to 110, how many one-step equations auditioned today?

900

620

520

450

Answer 1

You can caluclate the unknowns in the equations when you have the same amount of equations as unknowns.
In this case you have two unknowns (one-step, and two-step), and two equations (hidden in the 'story')

Answer 2

x = one-step
y = two-step

So your first equation will be:
x + y = 1070
The second will be:
3*x - 2*y = 110