Aaron’s point totals in the first four of five basketball games were 15, 18, 19, and 12. how many points, t, must he score to have a mean point total of more than 16? insert symbol character

I'm not sure what is meant by inserting a symbol character but I can do the rest.
The mean point total (M) has to be at least 17. This could be expressed by M > 16. 

M>16 = 15+18+19+12+t/5

Multiply both sides by 5:

M>80 = 15+18+19+12+t
M>80 = 64 + t

Subtract 64 from both sides:
M>16= t

t must be at least 17 (so t>16) for the mean to be bigger than 16. 

I hope that helps.