To determine the number of miles \( x \) in Arianys's taxi ride, we can create an equation based on the information given.
The taxi fare is comprised of a pick-up fee plus a charge per mile. The total fare can be represented as:
\[ \text{Total Fare} = \text{Pick-up fee} + (\text{Cost per mile} \times \text{Number of miles}) \]
According to the problem:
- The pick-up fee is $1.70.
- The cost per mile is $1.00.
- The total fare is $19.70.
We can set up the equation as follows:
\[ 19.70 = 1.70 + 1.00x \]
Now, to solve for \( x \):
- Subtract the pick-up fee from both sides:
\[ 19.70 - 1.70 = 1.00x \]
\[ 18.00 = 1.00x \]
- Divide both sides by 1.00:
\[ x = 18.00 \]
So, the number of miles in the taxi ride is \( \boxed{18} \).