Step-by-step explanation:
[tex]{ \huge{ \{}}{ \rm{ [(30 - 60) \div ( - 30)] {}^{2} - 15{ \huge{ \}}} \div ( - 7) }} \\ \\ \dashrightarrow \: { \huge{ \{}}{ \rm{[( - 30) \div ( - 30)] {}^{2}{ \huge{ \}}} \div ( - 7) }} \\ \\ \dashrightarrow \: { \huge{ \{}}{ \rm{[1] {}^{2} { \huge{ \}}} \div ( - 7)}} \\ \\ \dashrightarrow \: { \rm{1 \div ( - 7)}} \\ \\ { \boxed{ \boxed{ \rm{ \: - \frac{1}{7} \: \: }}}}[/tex]
