Answer: 9 hours
Step-by-step explanation:
Assuming they keep earning money at the same rate, we will set up a proportion to help us solve.
[tex]\displaystyle \frac{\$9,000}{4\;\text{hours}} =\frac{\$20,250}{x\;\text{hours}}[/tex]
Next, we will cross-multiply.
$9,000 * x = $20,250 * 4
$9,000x = $81,000
x = 9 hours
It will take the same restaurant about 9 hours to earn $20,250.
