急!!!數學~Power and Exponent

Evaluate and write the answer in faction (steps!!)
1) (4/5)^-2 ÷ (4/3)^0
Simplify (steps!!)
1) 81^x = 27 ^(x+2)
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show steps!!

1) At 9:00 a.m.,there are 600 bacteria in a culture. The number of bacteria in a
culture is given by the formal N=(600)(2^t) , where is the number of hours the culture has been growing. How many bacteria will there be at 4:00p.m. on the same day?