# Question #11699

The ratio of ${a}_{n + 1} / {a}_{n}$ is $\frac{3}{2}$.
A geometric progression (os geometric sequence) has terms in a common ratio: ${a}_{n + 1} / {a}_{n}$
In this case, we get $\frac{30}{20} = \frac{3}{2}$.
We can check by also calculating: $\frac{45}{30} = \frac{3 \times 15}{2 \times 15} = \frac{3}{2}$