5/8 * на одну целую 13/15 и * на две целых 2/7
5/8* 1 13/15* 2 2/7=5/8* 28/15*16/7=2240/840=8/3(сократили на 280)=2 2/3
5/8*1 13/15*2 2/7=5/8*28/15*16/7=8/3=2 2/3