The given series is: \( 97, 86, 73, 58, 45, \ldots \).
Step 1: Observe the difference between consecutive terms: \[ 97 - 86 = 11, \quad 86 - 73 = 13, \quad 73 - 58 = 15, \quad 58 - 45 = 13 \]
Step 2: The differences alternate between 11, 13, 15, and 13. If this pattern continues, the next difference should be 11.
Step 3: Subtract 11 from the last term 45: \[ 45 - 11 = 34 \] Thus, the next number in the series is 34.