How am I able to solve problems like this? Like is something I can just plug numbers into?

so for this type of problem you would want to use the Pythagorean theorem. its a squared plus b squared equals c squared. you use this because it makes a triangle. c is your hypotenuse which is the longest side of the triangle. so you plug in what you can and solve to find the missing variable. in this case, the base equals the square root of 80 or approximately 8.94