1) (2,8-2х):9=0,8
2,8-2х=0,8*9
2,8-2х=7,2
2,8-7,2=2х
-4,4=2х
х=(-4,4):2
х=-2,2.
<span>а) 158 - 392+75 - 158 - 75= (158-158)+(75-75)-392= -392
б) -4 11/56 + 1 7/40 - 2 5/18 + 4 11/56 - 1 7/40= (-4 11/56+ 4 11/56)+(1 7/40-1 7/40) - 2 5/18= -2 5/18</span>
1) 1/5 = 100/500
2) две
3) 6
4)а) 13/24
б) 19/36
413 - x/12 + 27 = 60
x/12 = 413 - 60 + 27
x/12 = 380
x = 380*12
x = 4560