PLEASE HELP ME WITH THIS!! I WILL GIVE EXTRA POINTS,AND BRAINLIST IF YOU ANSWER THIS CORRECTY!!

Katie has taken 5 math tests this year. On the first she scored a 75. The third test she scored 10 points more than the first two. The fourth test she scored 95 and the last test she scored 90.

What is Katie's average (mean) math score?
A. 86
B. 84
C. 69
D. 67
E. 65

MAKE SURE YOU EXPLAIN TO!!! THIS IS NOT ALL THE POINTS YOU WILL BE GETTING! THERE WILL BE MOREE!! :))