987 - 123
987 − 123<span> = </span><span>864</span>
<span>А)
3(7+2к)-4(-7+1/2к)=-19
21+6k+28-2k=-19
6k-2k=-19-21-28
4k=-68
k=-68:4
k=-17
===========
Б)
5/12(24х-144)-3/8(48х+44)=1,5</span>
10x-60-18x-16,5=1,5
10x-18x=1,5+60+16,5
-8x=78
x=78:(-8)
x=-9,75