Please help this is missing work and please show work I just need help with number 3, 9 and 8

Which steps could be part of the process in algebraically solving the system of equations, y+5x=x^2+10 and y=4x-10

Jonathan puts $400 in a bank account. each year the account earns 6% simple interest. how much interest will be earned in 5 years?

The relative growth rate for a certain type of fungi is 60% per hour.a small culture has formed and in just 6 hours the count shows to be 20,273 fungi in the culture.what is the initial number of fungi in the culture?