1. 81 : 3 = 27
2. 77 x 7 = 539
3.168 : 18 = 9
4.42 x 8 = 336
800b+1000000
200c+50000
232n+71224
412k+621k
a*(125+135) или 5a*(25+27)
500*(d+a)
d*(128+304)или 8d*(4+19)
a*(420+420)или 420*(a+a)
<span>3x-1=2(x-2)
3х-1=2х-4
3х-2х=-4+1
х=-3
</span>3(x+5)=7-5x
3х+15=7-5х
3х+5х=7-15
8х=-8
х=-8:8
х=-1
<span>7x-(3+2x)=x+9
7х-3-2х=х+9
7х-2х-х=9+3
4х=12
х=12:4
х=3
</span><span><span>13-(2x-5)=x-3</span>
13-2х+5=х-3
-2х-х=-3-13-5
-3х=-21
х=-21:(-3)
х=7
</span>
X+x-250+x-x-250=1800
2x-500=1800
2x=1800+500
2x=2300
x=2300:2
x=1150