The cholesterol levels of a group of young women at a university are normally distributed, with a mean of 188 and a standard deviation of 35. What percent of the young women have the following cholesterol levels? (For each answer, enter a number. Round your answers to one decimal place.)

(a) greater than 219
%

(b) between 192 and 220
%

So the first thing we do is to multiply the top equation by 3. the reason i want to do this is i notice there will be a 6y on both equations and can possibly add/subtract them. so we get 6y = -3x + 27. adding that and the second equation we get 6x = 27-15 which is 12. divide by 6 and we get 2. ∴ x = 2. substituting 2 into the first equation we get 2y = -2 + 9 which is 7. divide by 2 and we get 7/2. ∴ y = 7/2, x = 2.