Explanation:

The amount of money that Omar brought on vacation was $x$ and 35% of $x$ is $63. This can be written as an equation: $x \times \frac{35}{100} = 63$Multiply both sides by $\frac{100}{35}$. $x = 63 \times \frac{100}{35}$$x = \frac{6300}{35}$$x = 180$If the amount of money that Omar brought on vacation was $180 out of which he spent $63, the balance amount is $180 - 63$which is $117.