Răspuns:
{ a , b } i.p { 5 , 3 }
5a = 3b = K
5a = K => a = K / 5
3b = K => b = K / 3
( 3a + b ) / ( 2b - a ) = ( 3 · K / 5 + K / 3 ) / ( 2 · K / 3 - K / 5 )
= ( 3K / 5 + K / 3 ) / ( 2K / 3 - K / 5 )
= ( 9K / 15 + 5K / 15 ) / ( 10K / 15 - 3K / 15 )
= ( 14K / 15) / ( 7K / 15 )
= ( 14K / 15 ) · ( 15 / 7K )
= 2 / 15 · 15 / 1
= 2 / 1 · 1 / 1
= 2