ANSWER
$24
EXPLANATION
You had $30 yesterday and you spent 20% of it today.
Since you spent 20% of it, the percentage you will have left is:
100 - 20 = 80%
So, you have 80% of $30.
That is:
[tex]\frac{80}{100}\cdot\text{ 30 = \$24}[/tex]You have $24 left.
