Вычислите устно:
- \(\begin{array}{}{\largeа)}\\[13.2ex]\\\end{array}\)\(\begin{array}{r}320+180\\:\ 20\\\cdot\ 6\\-\ 80\\\cdot\ 13\\\hline?\end{array}\)
- \(\begin{array}{}{\largeб)}\\[13.2ex]\\\end{array}\)\(\begin{array}{r}630:90\\\cdot\ 60\\+\ 180\\:\ 15\\\cdot\ 25\\\hline?\end{array}\)
- \(\begin{array}{}{\largeв)}\\[13.2ex]\\\end{array}\)\(\begin{array}{r}3{,}5+4{,}5\\:\ 10\\-\ 0{,}3\\\cdot\ 17\\+\ 2{,}5\\\hline?\end{array}\)
- \(\begin{array}{}{\largeг)}\\[13.2ex]\\\end{array}\)\(\begin{array}{r}0{,}5\cdot1{,}8\\-\ 0{,}15\\:\ 0{,}3\\+\ 5{,}5\\:\ 1{,}6\\\hline?\end{array}\)