[tex]4,2*0,3+0,418:0,05=\frac{42}{10} *\frac3{10}+\frac{418}{1000}:\frac{5}{100}= \frac{126}{100}+ \frac{418}{1000}*\frac{100}{5}=1,26+\frac{418}{1000}*20=1,26+\frac{418}{50}=1,26+\frac{836}{100}=1,26+8,36=9,62\\\\(0,75+\frac{2,1}{4} )*\frac{7}{10} :10=(0,75+\frac{21}{10}*\frac14 )*\frac{7}{10} :10=(0,75+\frac{21}{40} )*\frac{7}{10} :10=\\\\(0,75+\frac{525}{1000})*\frac{7}{10} :10=(0,75+0,525)*\frac{7}{10} :10=1,275*\frac{7}{10} :10=\frac{1275}{1000}*\frac{7}{10} :10=\\\\[/tex]
[tex]= \frac{8925}{10000}:10=\frac{8925}{100000}=0,08925[/tex]
