x / y = 3 /4 atunci x / 3 = y / 4 = k ⇒ x = 3k
y = 4k
( 2x - y) / ( 5x - 3y ) = ( 6k - 4k ) / ( 15k - 12k) = 2k / 3k = 2 / 3
daca x / y = 2 / 3 atunci x / 2 = y / 3 = k ⇒ x = 2k
y = 3k
( 5x - 3y ) / ( 2x + y) = ( 10k - 9k ) / ( 4k + 3k) = k / 7k = 1 / 7