I'm reviewing for calculus and I've been stuck on this problem for a couple days. Can't seem to figure it out. I keep coming up with ln2.4 = x - x which is just silly, or x = √(400ln2.4) ≈ 18.7. I know the answer is x ≈ 12.5. But I can't figure out the correct process. 1. The problem statement, all variables and given/known data 24 = 10(ex/20 + e-x/20) 2. Relevant equations 3. The attempt at a solution 2.4 = ex/20 + e-x/20 ln2.4 ≠ x/20 - x/20 I tried using ex/20 = ex - e20 but I don't think this is right either. Came up with 20.69 - ln e-x = x and this is just another silly answer. I must be forgetting some rule. It seems to me like the variables keep canceling out, which I know can't be right.