Twice the sum of three and a number is 30. Find the number

The sum of two numbers is 12 and their difference is 18 what are the two numbers

Assume that adults have iq scores that are normally distributed with a mean of mu equals 100 and a standard deviation sigma equals 20. find the probability that a randomly selected adult has an iq between 80 and 120.assume that adults have iq scores that are normally distributed with a mean of mu equals 100 and a standard deviation sigma equals 20. find the probability that a randomly selected adult has an iq between 80 and 120.

Me i'm timed right now! a. (0,-5)b. (0,-3)c. (0,3) d. (0,5)