Answer:
12
Step-by-step explanation:
Let x be the number of gallons of water in lake Mead.
Given that there is 326099 gallons in 1 acre-foot, we calculate Mead's gallons as:
[tex]1 acrefoot=326099g\\28945000acrefoot=x\\\\x=\frac{28945000acrefoot\times326099g}{1acrefoot}\\\\x=9.4\times 10^{12} \ gallons[/tex]
We now equate x to [tex]9.4\times10^a[/tex];
[tex]9.4\times 10^a=9.4\times 10^{12}\\\\a=12[/tex]
Hence, a=12
