How many ways can choose 7 friends to be invited to the party out of 20 total friends?

Each of the 7 friends could be present or not present (2 cases) at the party giving total of  27  scenarios.

Since at least one must be present we exclude the case that none of them is present. So the answer would be:

27−1=127.

Step-by-step explanation:

i actually dont know but can you report me and dont ask

14

step-by-step explanation:

the multiples of 15 are 15, 30,45, 60, 75, 90, 105, 120, 135, 150, 165, 180, 195,   210, 225, 240, 255, 270, 285, 300, 315, 330, 345, 360, 375,   390, 405, 420, 435, 450, 465, 480, 495, 510, 525, 540, 555, 570, 585, 600, 615, 630, 645, 660, 675, 690, 705, 720, and 735.

the factors of 15 are 1, 3, 5, and 15.

hope that , fam!

-une, your fren : )