I think it is 555??
355+200=555
1 coin is 4 ways
2 coins is 4*3 ways
3 coins is 4*3*2 ways
4 coins is 4*3*2*1 ways
so total is 4+12+24+24=64 sums
The situations can be represented by the exponential function f(x)=60x1.15^x
After 7.86 years the value of the investment will be three times the initial value (If you round to the nearest dollar)
After 8 years the value of the investment will be $184.00 (If you round to the nearest dollar)