How many combinations of 4 students can a teacher choose from 30 students? a. 27,405 b. 120 c. 657,720 d. 810,000

With this question! what is process of elimination? ? p. s. my brothers acc got banned so add his new one @ yamauchiyamyam17

Simplify. −4x^2 (5x^4−3x^2+x−2) −20x^6−12x^4+8x^3−8x^2 −20x^6+12x^4−4x^3+8x^2 −20x^8+12x^4−4x^2+8x −20x^6+12x^4+4x^3−8x^2

What is 1.5% of 120 or what number is 1.5% of 120