Su Lin 和 Tina 在 2 天内做了一些项链。周一，Su Lin 比 Tina 多做了 17 条项链。周二，Su Lin 做了 30 条项链，Tina 做了 11 条项链。在这 2 天结束时，Tina 做的项链数量占总数的 $\frac{1}{4}$。Su Lin 做了多少条项链？

1. Find the difference in the number of necklaces made by Su Lin and Tina on Tuesday.

Difference on Tuesday = $30 - 11 = 19$

2. Find the total difference in the number of necklaces made over the 2 days.

Total difference = $17 + 19 = 36$
Su Lin made $36$ more necklaces than Tina in total.

3. Express the number of necklaces each made in units based on the given fraction.

Tina made $\frac{1}{4}$ of the total.
This means Tina made $1$ unit and the total is $4$ units.
Su Lin made: $4 - 1 = 3$ units.
Difference in units = $3 - 1 = 2$ units.

4. Find the value of 1 unit.

$2 \text{ units} = 36$
$1 \text{ unit} = 36 \div 2 = 18$

5. Calculate the total number of necklaces Su Lin made.

Su Lin made $3$ units.
$3 \times 18 = 54$