Mr Tan had $20 more than Mr Lee at first. After Mr Tan spent $50 and Mr Lee spent half of his money, both of them had the same amount of money left. How much money did Mr Lee have at first? Ans: $___

1. Express the amounts left in terms of units

Let Mr Lee's amount of money left be $1$ unit.
Since Mr Lee spent half of his money, his initial amount was $2$ units.
Since both had the same amount left, Mr Tan also had $1$ unit left.

2. Form an equation using Mr Tan's initial amount

Mr Tan spent $\char36{}50$, so his initial amount was $1\text{ unit} + 50$.
We are given that Mr Tan had $\char36{}20$ more than Mr Lee at first, so Mr Tan's initial amount can also be expressed as $2\text{ units} + 20$.
Equating the two expressions for Mr Tan's initial amount:
$1\text{ unit} + 50 = 2\text{ units} + 20$

3. Solve for 1 unit and find Mr Lee's initial amount

$2\text{ units} - 1\text{ unit} = 50 - 20$
$1\text{ unit} = 30$
Mr Lee's initial amount = $2\text{ units} = 2 \times 30 = 60$