21/2+4 1/2÷(3 2/5-1 1/2÷у)=4 1/6 , !

21/2+4 1/2÷(3 2/5-1 1/2÷у)=4 1/6 (2•2+1)/2+ (2•4+1)/2 : { (3•5+2)/5- (1•2+1)/2 : у}= (4•6+1)/6 5/2+ 9/2 : { 17/5- 3/2: у} = 25/6 9/2: { 17/5- 3/2: у} = 25/6- (5•3)/(2•3) 9/2: { 17/5- 3/2: у} = 25/6- 15/6 9/2: {17/5- 3/2: у} = 10/6 9/2: 10/6= { 17/5- 3/2: у} 9/2• 6/10 = 17/5- 3/2: у сокращаем 2 и 6 на 2. 9/1• 3/10= 17/5- 3/2: у 27/10- 17/5= (-3/2: у) 27/10- (17•2)/(5•2)= (-3/2: у) 27/10- 34/10= (-3/2: у) -7/10 = (-3/2: у) -7/10• у= (-3/2) у= (-3/2): (-7/10) у= (-3/2)• (-10/7) сокращается 2 и 10 на 2; и будет (+) у= 3/1• 5/7 у= 15/7 у= 2 1/7 ответ. проверка 2 1/2+4 1/2÷(3 2/5-1 1/2÷у)=4 1/6 2 1/2+ 4 1/2: (3 2/5- 1 1/2: 2 1/7)= 4 1/6 2 1/2+ 4 1/2: (3 2/5- (1•2+1)/2: (2•7+1)/7) = 4 1/6 2 1/2+ 4 1/2: ( 3 2/5- 3/2: 15/7)= 4 1/6 2 1/2+ 4 1/2: (3 2/5- 3/2• 7/15)= 4 1/6 сокращаем 3 и 15 на 3. 2 1/2+ 4 1/2: ( (3•5+2)/5- 1/2• 7/5)= 4 1/6 2 1/2+ (4•2+1)/2 : (17/5- 7/10)= 4 1/6 2 1/2+ 9/2: ( (17•2)/(5•2)- 7/10)= 4 1/6 2 1/2+ 9/2: (34/10- 7/10)= 4 1/6 2 1/2+ 9/2: 27/10= 4 1/6 2 1/2+ 9/2• 10/27= 4 1/6 сокращаем 9 и 27 на 9, 2 и 10 на 2. 2 1/2+ 1/1• 5/3= 4 1/6 2 1/2+ 5/3= 4 1/6 2 1/2+ 1 2/3= 4 1/6 2 (1•3)/(2•3)+ 1 (2•2)/(3•2)= 4 1/6 2 3/6+ 1 4/6= 4 1/6 3 7/6= 4 1/6 4 1/6= 4 1/6

1) 32/30=1,07 (км/мин) машина 2) 1,07/4*3=0,8 (км/мин) мотоцикл 3) 32/0,8=40 мин надо мотоциклу чтобы проехать 32км