Since ABCD and EFGH are similar
∴ Their corresponding sides are proportion (have equal ratios)
∵ BC = 6 and FG = 3
∵ CD = 4
→ Substitute then in the 2nd and 3rd ratio above to find GH
→ By using cross multiplication
∴ 6 x GH = 3 x 4
∴ 6GH = 12
→ Divide both sides by 6 to find GH