Răspuns :
X/Y = 2/3 ==> X = 2Y/3
5X+7Y/ 9X-3Y =
= (10Y/3 + 7Y)/(18Y/3 - 3Y) =
= [(10Y+7×3Y)/3] /(6Y-3Y)=
= (10Y+21Y)/3 / 3Y =
= 31Y/9Y =
= 31/9
5X+7Y/ 9X-3Y =
= (10Y/3 + 7Y)/(18Y/3 - 3Y) =
= [(10Y+7×3Y)/3] /(6Y-3Y)=
= (10Y+21Y)/3 / 3Y =
= 31Y/9Y =
= 31/9