You have to round it to 21 which is the answer
When the 2 graphs are the same. It'll be infinitely many solutions.
System Equations are to find the intercepts of graphs so just think that when 2 graphs are same, that means they both intercept each others infinitely.
So the answer is clearly C.
Setting up a ratio
20 ft/7 ft
cannot be reduced ratio is the same as given
Consider a trapezoid GJKF with:
GH=JH (hypothesis)
FL=KL (hypothesis)
so HL is the median of trapezoid GJKF
so: HL=1/2(2.5+1.2)=1.85