What is the 11th term of the arithmetic sequence with the rule a, = - 2 +6(n-1)?

I’m stuck on this i don’t understand.

The distribution of the amount of money spent by students for textbooks in a semester is approximately normal in shape with a mean of $235 and a standard deviation of $20. according to the standard deviation rule, how much did almost all (99.7%) of the students spend on textbooks in a semester?

Write two point-slope equations for the line passing through the points (6, 5) and (3, 1)