(Compound value solving for n)

How many years will the following take?

a. $510 to grow to $1,202.55 if invested at 10 percent compounded annually

b. $38 to grow to $70.34 if invested at 8 percent compounded annually

c. $90 to grow to $440.82 if invested at 13 percent compounded annually

d. $58 to grow to $77.73 if invested at 5 percent compounded annually

Round to the nearest whole number