In order to conduct an experiment, 4 subjects are randomly selected from a group of 49 subjects. how many different groups of 4 subjects are possible?

What is the value of the digit 1 in the number 13?

Idon’t understand this.. will someone ? will mark brainliest along with 20 points.

If the graphs of the linear equations in a system are parallel, what does that mean about the possible solution(s) of the system? a. there are infinitely many solutions. b. there is no solution. c. there is exactly one solution. d. the lines in a system cannot be parallel.