How do you solve 5/a=30/54? Algebra Rational Equations and Functions Rational Equations Using Proportions 1 Answer iceman Jan 28, 2017 a=9 Explanation: 5/a=30/54 => simplify: 30/54=5/9 then: 5/a=5/9=>equal fractions with equal numerators, then the denominators must be equal so: a=9=> let's prove it: 5/a=5/9=>simplify further divide both sides by 5: 1/a=1/9=>cross multiply: 1*a=1*9=>or: a=9 Answer link Related questions How do you solve proportions? What is Rational Equations Using Proportions? How do you solve \frac{2x}{x+4}=\frac{5}{x}? How do you use cross multiplication to solve \frac{2}{x+3}-\frac{1}{x+4}=0? What is cross multiplication? How do you solve \frac{3x^2+2x-1}{x^2-1}=-2 using cross multiplication? How do you solve \frac{7x}{x-5}=\frac{x+3}{x}? How do you cross multiply \frac{4x}{x+2}=\frac{5}{9}? How do you solve 4/(x-3)=4? How do you find fractional notation for the ratio 1.6 to 9.8? See all questions in Rational Equations Using Proportions Impact of this question 3258 views around the world You can reuse this answer Creative Commons License