For the equation 21 + 3x = 3x + k, which value of k will create an equation with no solutions? PLEASE EXPLAIN YOUR ANSWER A LOT OF PEOPLE JUST SAY ANYTHING FOR POINTS i’ll give brainiest

A. x
B. 3x
C. 15
D. 21

Does the problem involve permutations or? combinations? do not solve. the matching section of an exam has 4 questions and 7 possible answers. in how many different ways can a student answer the 4 ? questions, if none of the answer choices can be? repeated?

Someone answer asap for ! a ball is rolled down a ramp. the height, f(x), in meters, of the ball x seconds after it is released is modeled by the function f(x) = x²- 10x + 25 for all values of x from 0 to 5. which statement about the ball is true? a. the maximum height of the ball is 5 meters b. the height of the ball increases from 0 to 5 meters above the ground. c. the ball has traveled 5 meters when it reaches the bottom of the ramp. d. the ball has been traveling for 5 seconds when it reaches the bottom of the ramp

Evan went to the park and saw for animals each animal was either a duck or dog if he saw a total of 14 legs how many of each animal did he see