Chapter 7 Exponential and Logarithmic Functions - 7.7 Write and Apply Exponential and Power Functions - 7.7 Exercises - Quiz for Lessons 7.6-7.7 - Page 536: 10

$y=\frac{5}{6}\cdot6^x$

Let $y=ab^x$. Then our equations are: $5=ab^1$ and $30=ab^2$. If we divide the second equation by the first one, we get: $6=b$. Then $5=a\cdot6^1=6a\\a=\frac{5}{6}$. Thus $y=\frac{5}{6}\cdot6^x$