The sum of two numbers is 15. Four times one of the numbers is twelve more than two times the other number. What are the two numbers?

Let a and b be our two numbers.Here is the set up:a + b = 15...........A4a = 2b + 12......BWe have a system of equations in two variables.Solve equation A for either a or b. I decided to solve for a.a + b = 15a = 15 - bPlug into equation B.4(15 - b) = 2b + 12Solve for b.60 - 4b = 2b + 12-4b - 2b = 12 - 60-6b = -12b = -12/-6b = 2We now know that b is 2. To find a, plug b = 2 into either equation A or B. As you can see, equation A is easier to deal with. a + b = 15a + 2 = 15a = 15 - 2a = 13The two missing numbers are 2 and 13.