Make each known side into a ratio like so...
75/6
(Because 75 is the shadow casted by the building, and 6 is the shadow casted by sarah)
and 50/x
(50 is how tall the building is and sarah's height is what needs to be found)
Therefore,
75 50
---- -----
6 x
Do cross products;
50 x 6 = 75 x X
300 = 75x
Divide by 75
x = 4ft
With any equation you are allowed to take the logarithm of both sides so
5^c=125 now take the logarithm base 5 to both sides giving.
log5(5^c)=log5(125), using the rule log(a^b)=a*log(b) you get
c log5(5)=log5(125), since log5(5)=1
c=log5(125)
The answer to the question is n>1/2.
2 goes into 400, that is

,
However, 2 goes into 400,
200 times.