In this case, choosing February 1, February 12, and February 20 would be the same thing as choosing February 12, February 1, and February 20. So, since order does not matter, we will use a combination to solve the question.
The formula for combinations is...
n! / [r!(n - r)!], where n = the number of days in February (28) and r = the number of days you are choosing (3).
its asking to write the equation in slope-intercept form so y=mx+b m in this case is -4 and b whihc is the y-intercept is 3 so you just write the equation y= -4x + 3
Like you can see in the picture, I like to set up a proportion, so 81 over X and 45 over 100. Then, you can cross multiply, so 81 x 100 = 8100 and then divide, 8100 ÷ 45 = 180, your answer!
