Concept:Expressing percentage increase as multiplication by a decimal factor.Explanation:Let the third number be x.The first number is 35% more than x, so it is x+0.35x=1.35x.The second number is 80% more than x, so it is x+0.80x=1.80x.Their ratio is 1.35x:1.80x.Divide both terms by 0.45x to simplify:0.45x1.35x:0.45x1.80x=3:4.Answer:3:4 (Option B)