So far it seems right. basically, your equation says:
The number (y) of bacteria is 1, and that multiplies by 10 times, as many times as there are days gone by (x) .
i.e. after one day, the bacteria has increased by a factor of 10....
So your second answer is correct.
Now, when is the number of bacteria equal to 100. Well, y is the number of bacteria, so
Depending on your grade, you either just KNOW that 10^2 is 100, or you use your log button. I won't go into that, in case you don't know about it.
The last part is the same...
Seems like you havent done logs yet, so .. whatever method your teacehr prefers