Russell is filling a cylinder-shaped swimming pool that has a diameter of 20 feet. He fills it with water to a depth of 3 feet. What is the volume of the water in the pool, to the nearest cubic foot? 377 cubic feet

942 cubic feet

2958 cubic feet

3768 cubic feet

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.