Look at this series: U32, V29, __, X23, Y20, ... What number should fill the blank?

This is a simple multiplication series. Each number is 2 times greater than the previous number.

This is a simple subtraction series; each number is 4 less than the previous number.

Two series alternate here, with every third number following a different pattern. In the main series, 3 is added to each number to arrive at the next. In the alternating series, 5 is subtracted from each number to arrive at the next.

In this series, the letters progress by 2, and the numbers increase by 2.

This series alternates the addition of 4 with the subtraction of 3.

The wing, fin, and rudder are all parts of an airplane.

The core, seeds, and pulp are all parts of an apple. A slice would be a piece taken out of an apple.

A peninsula, island, and cape are all landforms; a bay is a body of water.

Fair, just, and equitable are all synonyms meaning impartial. Favorable means expressing approval.

Unique, rare, and exceptional are all synonyms. Beautiful has a different meaning.