Answer:
5.93 * 10^7
7 represents the amount of times you moved the decimal
900=300(1+0.058)^t divide each side by 300
3=1.059^t
Log(3)=t*log(1.058)
T=log(3)/log(1.058)
T==19.5 years
12.4 is the answer for both
Remark
I would have had the answer a whole lot sooner if I would have read the question properly. The figure in the circle is called a cyclic quadrilateral. It has the odd property that the angles that are opposite each other add up to 180o.
So DEB + DCB = 180o
DEB = 180 - 87
DEB = 93o
Note: The arcs marked 60 and 76 have nothing whatever to do with this problem.