(0.988+x)×2.5=4.87
0,988+x=1,948
x=1,948-0,988
x=0,96
11.2:(х+2/15)=6
x+2/15 =11,2:6
x+2/15 =1 13/15
x= 1 13/15 - 2/15
x = 1 11/15
(х+8/27):19целых5/9=1/12
x+8/27 = 1/12 * 19 5/9
x+8/27 = 1/12 * 176/9
x+8/27 = 44/27
x=44/27 - 8/27
x=36/27
x= 1целая1/3