Resposta:
Olá bom dia!
Lembre que 0,3 = [tex]\frac{3}{10}[/tex]
[tex]a) \\\\(\frac{5}{6} .\frac{7}{10}) .\frac{3}{10} \\\\\frac{35}{60} .\frac{3}{10} = \frac{7}{20} .\frac{1}{2} = \frac{7}{40}[/tex]
[tex]b)\\\\15:\sqrt{25} -\sqrt{36} +4:\sqrt{16} - 1\\\\3:5 -6 + 4:4-1\\\\\frac{3}{5} -6+1-1\\\\\frac{3 - 30}{5} + 0\\\\-\frac{27}{5}[/tex]
