3e^-y*0.5 + 3e^-y*1.0 + 3e^-y*1.5 + 3e^-y*2.0 = 98.39

This equation can be solved using an iterative ("trial and error") procedure to give y = 6.76%.

My teacher explained to me that this equation cannot be done by hand and that the y solution can only be resolved by using SOLVER on EXCEL. As I was trying to use it it showed me many options under =SOLVER. Can anybody explain how to use SOLVER on EXCEL and how to come up to the 6.76% solution? Highly appreciate it and thank you!