Răspuns:
Explicație pas cu pas:
x/y = 2/3 => 3 x = 2 y => x/2 = y/3 = k -> coeficient de proportionalitate
=> x = 2 k; y = 3 k
___________________
(5 x - 2 y ) /( 7x - 3y) = 4/5
= (5 × 2 k - 2 × 3 k ) / ( 7×2k - 3×3k) =
= (10k - 6k ) /(14k-9k) =
= 4k / 5k =
= 4/5
