There are 30 students in Mr Magorium's discrete mathematics class: 23 of his students major in mathematics, 12 major in physics, and 3 major in subjects outside of math and physics. How many double major in mathematics and physics?
If you remove the three students who do not major in either math or physics, you will have 30 - 3 = 27 students.
If you add the 23 who major in math to the 12 that major in physics, you get 23 + 12 = 35 students.
But there are only 27 students, so 35 - 27 = 8 must have a double major in math and physics.
If you remove the three students who do not major in either math or physics, you will have 30 - 3 = 27 students.
If you add the 23 who major in math to the 12 that major in physics, you get 23 + 12 = 35 students.
But there are only 27 students, so 35 - 27 = 8 must have a double major in math and physics.