\(4000 = 3000(1+(x/400))^8\)
Divide both sides by 3000 to get
4000/3000 = (1 + (x/400)^8
4/3 = (1+(x/400)^8 Now take the 8th root of both sides
(4/3)^1/8 = 1+x/400
1.0366146 = 1 + x/400
.0366146 = x/400
14.6459 =x
+37146 
