$\begin{array} { l }r=\frac{ 30 }{ 60 },\\r=\frac{ 15 }{ 30 },\\r=\frac{ \frac{ 15 }{ 2 } }{ 15 }\end{array}$
Cancel out the common factor $30$$\begin{array} { l }r=\frac{ 1 }{ 2 },\\r=\frac{ 15 }{ 30 },\\r=\frac{ \frac{ 15 }{ 2 } }{ 15 }\end{array}$
Cancel out the common factor $15$$\begin{array} { l }r=\frac{ 1 }{ 2 },\\r=\frac{ 1 }{ 2 },\\r=\frac{ \frac{ 15 }{ 2 } }{ 15 }\end{array}$
Simplify the complex fraction$\begin{array} { l }r=\frac{ 1 }{ 2 },\\r=\frac{ 1 }{ 2 },\\r=\frac{ 1 }{ 2 }\end{array}$
Since the ratio between each pair of consecutive terms is the same, the sequence is geometric and the common ratio is $r=\frac{ 1 }{ 2 }$$r=\frac{ 1 }{ 2 }$
Substitute the first term $a_1=60$ and the common ratio $r=\frac{ 1 }{ 2 }$ into the formula for the $n$-th term of a geometric sequence, $a_n=a_1{r}^{n-1}$$a_n=60 \times {\left( \frac{ 1 }{ 2 } \right)}^{n-1}$