Explanation:

To solve this problem, we need to set up equations based on the information given:

- Monkeys have 1 head and 4 legs. Humans have 1 head and 2 legs.

- Let's denote the number of monkeys as M and the number of humans as H.

Based on the count of heads:

- \( M + H = 54 \)

Based on the count of legs:

- \( 4M + 2H = 148 \)

Solving these equations:

1. From the first equation: \( H = 54 - M \)

2. Substitute \( H \) in the second equation:

- \( 4M + 2(54 - M) = 148 \)

- \( 4M + 108 - 2M = 148 \)

- \( 2M = 40 \)

- \( M = 20 \)

- The calculation shows that there are 20 monkeys.

- Option:1, 20

- Option:2, 16

- Option:3, 18

- Option:4, 14