三个数的和是 60。如果第二个数是第一个数的 $\frac{1}{6}$，且第三个数是第二个数的 3 倍，求第一个数。 答案：___

1. Express the three numbers in terms of units

Let the first number be $6$ units.
Second number = $\frac{1}{6} \times 6$ units = $1$ unit.
Third number = $3 \times 1$ unit = $3$ units.

2. Find the total number of units and equate to the given sum

Total units = $6 + 1 + 3 = 10$ units.
$10$ units = $60$

3. Find the value of 1 unit and calculate the first number

$1$ unit = $60 \div 10 = 6$
First number = $6$ units = $6 \times 6 = 36$