A university student is selecting courses for his next semester. He can choose from 4 humanities courses and 8 science courses. In how many ways can he choose 5 courses if more than 3 must be humanities courses?

y/x=18

step-by-step explanation:

-22

times both sides by 2, times () by 8, add alile terms, move terms, add alike and caculate divide both sides by 3

or

step-by-step explanation:

we need to solve for 'x' the following equation:  

we have that:

⇒

⇒ ⇒

factorizing, we get that:

  ⇒

then, the solutions are: or

nothing extraneous has been found!