I need help due asap

Solve 3x-18=2y and 5x-6y=6 by elimination show work

Scores on a university exam are normally distributed with a mean of 78 and a standard deviation of 8. the professor teaching the class declares that a score of 70 or higher is required for a grade of at least “c.” using the 68-95-99.7 rule, what percentage of students failed to earn a grade of at least “c”?

2,10,-50 next two numbers geometric sequence