Resposta :
[tex]1 - A)\\\frac{30}{10}\\\\\mathrm{Dividir:}\:\frac{30}{10}=3[/tex]
[tex]B)\\\frac{-12}{-3}\\\\=\frac{12}{3}\\\\\mathrm{Dividir:}\:\frac{12}{3}=4[/tex]
[tex]C)\\\frac{15}{-5}\\\\\frac{15}{-5}\\\\\mathrm{Dividir:}\:\frac{15}{5}=3[/tex]
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[tex]2 - A)\\3+6\cdot \:2-\frac{15}{-3}\\\\=3+12-\left(-5\right)\\\\=3+12+5\\\\=20[/tex]
[tex]B)\\2+\left[3\div \left(10-11\right)+1\right]\div \:2\\\\=2-2\div \:2\\\\=2-1\\\\=1[/tex]
[tex]C)\\5\left(8-5\right)\left(2+7\right)=\\\\=5\cdot \:3\left(2+7\right)\\\\=5\cdot \:3\cdot \:9\\\\=135[/tex]