Predicted by Model y=10x

Jack is considering a list of features and fees for denver bank. jack plans on using network atms about 4 times per month. what would be jack’s total estimated annual fees for a checking account with direct paycheck deposit, one overdraft per year, and no 2nd copies of statements?

X+ y = 5 ; x - y =3 solve using linear combination

Solve this riddle: i am an odd number. i an less than 100. the some of my digit is 12. i am a multiple of 15. what number am i?