Matthew goes hiking every 12 days and swimming every nine days he did both kinds of exercise today how many days from now will you go both hiking and swimming again

The number of chocolate chips in an 18-ounce bag of chocolate chip cookies is approximately normally distributed with a mean of 1252 chips and standard deviation 129 chips. (a) what is the probability that a randomly selected bag contains between 1100 and 1500 chocolate chips, inclusive? (b) what is the probability that a randomly selected bag contains fewer than 1125 chocolate chips? (c) what proportion of bags contains more than 1225 chocolate chips? (d) what is the percentile rank of a bag that contains 1425 chocolate chips?

Don't know how to find x given these segment lengths

What is the result of adding the system of equations? 2x+y=4 3x-y=6