The formula for exponential growth is y=a(1+r)[tex] ^{x} [/tex]. Where a is the initial value when time is 0 (100 in this case). r is the growth rate, we can see that the growth is 10%. And x is how much time has passed, we want to find out how many trucks after 9 years.
So we would plug the values in to get y=100(1+.1)[tex] ^{9} [/tex]. Solving this gives us 235.79, so we would round up to 236, and our answer would be 236 trucks registered in the city in year 9.
Edit: The x and the 9 are exponents, the formatting made them look a bit weird.
