I'm attaching the problem as a png. The top half is the question whereas the second half is the solution. I understand everything about the question until the ultimate answer the final answer is: (r (constant) x0(constant) / k (constant)) * (1 - e^-60t) as shown. However I don't understand why my answer differs. I concluded the problem with (r (constant) x0(constant) / k (constant)) * (-e^-60t) This doesn't seem to be a basic algebra issue, and It is beyond my comprehension. Thank you.