722.
1) 3,75+2 1/2 = 3,75+2,5=6,25=6 1/4= 25/4
2) 2 1/3 -1,875= 2 1/3 -1 7/8 = 2 8/24 -1 21/24 = 11/24
3) 25/4 : 11/24 = 25*24/(4*11) = 150/11
4) 2,75-1 1/2 =2,75-1,5=1,25=5/4
5) 8 1/8+1,5 =8 1/8 + 1 4/8 = 9 5/8 =77/8
6) 5/4 : 77/8 = 5*8/(4*77) = 10/77
7) 150/11 -10/77 = 1050/77 - 10/77 = 1040/77
8) 1040/77 :10/11 = 1040*11/(77*10) =104/7 = 14 6/7
724.
2(1+x) -5(2x-y) = 2*5*(3y-1)
6(5y-2) -2(4x-5) = 2*6*(8-2x)
2+2x-10x+5y = 30y-10
30y-12-8x+10= 96-24x
2-8x=30y-5y-10
30y -2 =96-16x
8x+25y = 12 ( *-2)
16x+30y = 98
-16x-50y= -24
16x+30y= 98 (сложим)
-20y= 74
8x+25y=12
y= -74/20
8x+25y=12
y= -3 14/20 = -3,7
x= (12-25y)/8
x=(12+3.7*25)/8=13,0625 = 13 1/16
1/8-1/12=1/24 часть бассейна наполнится через вторую трубу за час.
Ответ: 1/24 часть.
А) 1 - 4/9 = 1/1 - 4/9 = 9 - 4/9 = 5/9
б) 8 8/15 - 4 9/20 = 128/15 - 89/20 = 512 - 267/60 = 245/60 = 49/12
в) 4/1 - 3 3/4 = 4/1 - 15/4 = 16 - 15/4 = 1/4
г) 9 4/21 - 4 11/14 = 193/21 - 67/14 = 386 - 201/42 = 185/42
д) 7 1/10 - 3 1/6 = 71/10 - 19/6 = 213 - 95/30 = 118/30 = 59/15
е) 5 5/33 - 4 1/2 = 170/33 - 9/2 = 340 - 297/66 = 43/66
108/92=42/b
108b=42*92
b=42*92/108
b=35,777777
37 16
32 2
5(ост.)
49 16
48 3
1(ост.)
68 16
64 4
4(ост.)
82 16
80 5
2(ост.)
99 16
96 6
3(ост.)