а) 15x = 0,15
\[x = \frac{0.15}{15} = 0.01\]
б) 3,08 : y = 4
\[y = \frac{3.08}{4} = 0.77\]
в) За + 8а = 1,87
11a = 1,87
\[a = \frac{1.87}{11} = 0.17\]
г) 7z - 3z = 5,12
4z = 5,12
\[z = \frac{5.12}{4} = 1.28\]
Ответ: a) x = 0.01; б) y = 0.77; в) a = 0.17; г) z = 1.28