There are ten people in the Baking Club, including Mark. They choose $3$ people to form an executive committee. How many possible committees can be formed?

120 ways

Step-by-step explanation:

Number of people in baking club = 10

Number of people who make up an executive committee = 3

Number of committees which can be formed :

This is a combination problem:

nCr = n! / (n-r)! r!

n = 10 ; r = 3

10C3 = 10! / (10 - 3)! 3!

= 10! / 7! 3!

= ( 10 * 9 * 8) / 3 * 2 * 1

= 720 / 6

= 120 ways

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.

is means division by fractions

step-by-step explanation: