Question

I really don't understand this. Can someone answer and explain?

Answer 1

ABCD ∽ EFGH, meaning both quadrilaterals are similar, therefore the proportionos of their corresponding sides are equal, thus

`\cfrac{AB}{EF}~~ = ~~\cfrac{CD}{HG}\implies \cfrac{\stackrel{AB}{3}}{\underset{EF}{2}}~~ = ~~\cfrac{\stackrel{CD}{4.5}}{\underset{HG}{y}}\implies 3y=9\implies y=\cfrac{9}{3}\implies y=3`