its the first option.
tiles of X and tiles of 1 are different
3 tiles of "X" = 3X
3 tiles of " 1 " = 3
option 3 does not mean 3X, it just means 3X + 3
The answer is a 40% discount because it costs $24 less than the original price and 24 divided by 60 is .4 or 40%!
<span>The method of solving "by substitution" works by solving one of the equations (you choose which one) for one of the variables (you choose which one), and then plugging this back into the other equation, "substituting" for the chosen variable and solving for the other. Then you back-solve for the first variable.</span>