21:7=3 Так же ............
A) <span>-3.1a + 2.25b - a - 1.4b + 6.3a = 2,2а +0,85b
</span>b) <span>3/8(2,4х-3,2у)-1,8(5/9х+1,5у) =3/8 * 12/5x - 3/8 * 16/5у - 9/5 * 5/9х - 9/5 * 3/2у = 9/10х - 6/5у - х - 27/10у = -1/10х -39/10у =-0,1х - 3,9у</span>
2)
=2ц 3/24+3ц 10/24=5ц 13/24
4)
=5ц 52/60+1ц 35/60=7ц 27/60=7ц 9/20
6)
=32/36-21/36=11/36
8)
=7ц 9/24-5ц 20/24=1ц 13/24
10)
=21/10*15/14=9/4=2ц 1/4
12)
=18/5*10/9=4
14)
=5/7*8/3=40/21=1ц 19/21
x/2=3/7 х = 2 *3 / 7 = 6/7
x/3=2/5 х = 3 * 2 / 5 = 6/5 = 1 1/5
x/12=7/10 х = 12 * 7 / 10 = 8 4/10 = 8 2/5
x/16=9/32 х = 16 * 9 / 32 = 9/2 = 4 1/2