## Basic College Mathematics (9th Edition)

The number is $9$.
Let $x=$ the number $\frac{1}{3}x + 3x = 30$ $\frac{x}{3} + 3x = 30$ $x + (3x \times 3) = (30 \times 3)$ $x + 9x = 90$ $10x = 90$ $x = \frac{90}{10}$ $x = 9$