18 ÷ 2 x 9 + 24 - 5 = 100

16
Each number reverses the previous number and adds 1 to each digit. Thus, in the first two
terms, 16 reversed is 61, which then changes to 72. In the penultimate term, 50 reversed
becomes 05, which in turn becomes 16 – by adding 1 to each digit.

Married couples

Clouds

NOON

XIX-I=XX or -19-1=20

Towel

Copper

The hairdresser who has badly cut hair, because the hairdressers cut their hair each other.

6561
There are two sequences arranged alternately. In each sequence the number is the square of the previous number in that sequence. 561 is the square of 81.

A plate

1, only the truck. The cars were going in the opposite direction.