7.158 * 10^9 rounds to 7 * 10^9
7 * 10^9 = 7,000,000,000
Here's link to the answer:

So the probability is the number of favorable outcomes divided by the number of total outcomes. This means that the favorable outcomes are 7/9, and the unfavorable outcomes are 2/9. The odds against the event are the unfavorable outcomes. Therefore the odds against the event is 2/9, or 0.2 repeating. Hope this helps. Feel free to ask more questions, and feel free to ask questions about my explanation.
first off let's convert the mixed fractions to improper fractions.

she already did half a hat, so we can say 
so she only needs enough fabric to make 3 more full hats, we know each one uses 9/7 ft, so
