Let’s solve the proportion three-fifths equals some number over 100.
We can view this equal sign like a scale, a balance. Three-fifths has to be exactly equal to something over 100. They need to have the same value.
When that’s the case, these are equivalent fractions; they’re fractions with the same value. Moving from five to 100, we can ask the question, what would we multiply by five to equal 100? The answer is 20. When we multiply five by 20, it equals 100.
For fractions to be equivalent, we would multiply the numerator and the denominator by the same amount. To keep this thing balanced, we need to multiply three by 20 as well. Three times 20 equals 60. And three-fifths equals 60 one hundredths.