一群孩子被分在两个礼堂中，礼堂 A 和礼堂 B。礼堂 A 中的孩子人数与礼堂 B 中的孩子人数之比为 3 : 8。在礼堂 A 中，男生人数与女生人数之比为 5 : 2。礼堂 A 中有 18 名女生。求两个礼堂中的孩子总数。 答：___

1. Find the number of boys in Hall A

Given the ratio of boys to girls in Hall A is $5 : 2$, and there are 18 girls in Hall A:
$2\text{ units} = 18$
$1\text{ unit} = 18 \div 2 = 9$
$\text{Number of boys} = 5 \times 9 = 45$

2. Find the total number of children in Hall A

$\text{Total in Hall A} = 45 + 18 = 63$ (or $7 \times 9 = 63$ children)

3. Find the total number of children in both halls

The ratio of children in Hall A to Hall B is $3 : 8$.
$3\text{ parts} = 63$
$1\text{ part} = 63 \div 3 = 21$
$\text{Total parts for both halls} = 3 + 8 = 11$
$\text{Total children} = 11 \times 21 = 198$