Пошаговое объяснение:
1) 3/4 +5/8 = (6+5)/8= 11/8 = 1 3/8
2) 2/5 + 7/15 = (6+7)/15= 13/15
3) 7/16 +1/4 = (7+4)/16= 11/16
4) 2/7 +1/3 = (6+7)/21= 13/21
5) 5/18 + 2/3 = (5+12)/18= 17/18
6) 5/6+ 7/8 = ( 20+21)/24 = 41/24 = 1 17/24
7) 5/6 + 2/9 = (15+4)/18= 19/18 = 1 1/18
8) 1/4+2/5 = (5+8)/20= 13/20
1) (7/15 - 1/6)+ 2/5= (14-5)/30 + 2/5= 9/30+2/5= (9+12)/30= 21/30= 7/10
2) (3/8- 1/9) + 25/36= (27- 8)/72+25/36= 19/72+25/36= (19+50)/72=69/72
3) (8/9- 5/6)+2/3 = (16 -15)/18 + 2/3= 1/18 + 2/3= (1+12)/18= 13/18
4) (7/8 - 13/20)+9/10 = (35-26)/40+ 9/10= 9/40 +9/10=(9+36)/40=45/40= 1 1/8
5) (7/18- 1/12)+5/6= (14-3)/36 + 5/6= 11/36+5/6= (11+30)/36=41/36= 1 5/36
6) (3/4 - 8/15) +17/20= (45-32)/60 + 17/20= 13/60+17/20= (13+51)/60=
=64/60= 1 1/15
v + v₀ - скорость баржи по течению весной
v - v₀ - скорость баржи против течения весной
v + v₀ - 1 - скорость баржи по течению летом
v - v₀ + 1 - скорость баржи против течения летом
Тогда: { v + v₀ = 5(v - v₀)
{ v + v₀ - 1 = 3(v - v₀ + 1)
{ v =1,5v₀
{ 1,5v₀ + v₀ - 1 = 4,5v₀ - 3v₀ + 3
2,5v₀ - 1,5v₀ = 4
v₀ = 4 (км/ч) - скорость течения весной
v + 4 - 1 = 3(v - 4 + 1)
v + 3 = 3v - 9
12 = 2v
v = 6 (км/ч) - скорость баржи
ответ: скорость течения весной - 4 км/ч.
Пошаговое объяснение:
1) 3/4 +5/8 = (6+5)/8= 11/8 = 1 3/8
2) 2/5 + 7/15 = (6+7)/15= 13/15
3) 7/16 +1/4 = (7+4)/16= 11/16
4) 2/7 +1/3 = (6+7)/21= 13/21
5) 5/18 + 2/3 = (5+12)/18= 17/18
6) 5/6+ 7/8 = ( 20+21)/24 = 41/24 = 1 17/24
7) 5/6 + 2/9 = (15+4)/18= 19/18 = 1 1/18
8) 1/4+2/5 = (5+8)/20= 13/20
1) (7/15 - 1/6)+ 2/5= (14-5)/30 + 2/5= 9/30+2/5= (9+12)/30= 21/30= 7/10
2) (3/8- 1/9) + 25/36= (27- 8)/72+25/36= 19/72+25/36= (19+50)/72=69/72
3) (8/9- 5/6)+2/3 = (16 -15)/18 + 2/3= 1/18 + 2/3= (1+12)/18= 13/18
4) (7/8 - 13/20)+9/10 = (35-26)/40+ 9/10= 9/40 +9/10=(9+36)/40=45/40= 1 1/8
5) (7/18- 1/12)+5/6= (14-3)/36 + 5/6= 11/36+5/6= (11+30)/36=41/36= 1 5/36
6) (3/4 - 8/15) +17/20= (45-32)/60 + 17/20= 13/60+17/20= (13+51)/60=
=64/60= 1 1/15