Hi!
We need to know how much money we have to spend besides the $39.99. So subtract.
45-39.99=5.01
Now find how many texts you can send with $5.01.
5.01/0.15=33.36666
But you can't send 0.3666 of a text, so the answer is 33.
Hope this helps! :)
-Petedhel