Variables expression for 2x+a

I'm terrible at math any here is appreciated.

Iq scores for adults age 20 to 34 years are normally distributed according to n(120, 20). in what range does the middle 68% of people in this group score on the test?

Aflower has 26 chromosomes. to create a new flower, how many chromosomes would a sperm cell have? what is this process called? part 2: within a flower cell that has 26 chromosomes, how many chromosomes would a cell that is created within the stem of a flower as it grows, have? what is this process called?