y = original value • growth ^(time/period of growth)
30000000000000 = 15000000000000 • (1+0.02)^(x/1)
Divide both sides by 15 trillion
2 = (1.02)^(x)
take logarithm of both sides
log2 = log1.02^x
Bring x down using log law
log2 = xlog1.02
Divide both sides by log1.02
x = 35
35 years