Which matrix can be used to solve the system? x+y=21 5x+4y=20 a) [x]=[4 -1][21] [y]=[-5 1][20] b) [x]=[-4 1][21] [y]=[5 -1][20] c) [x]=[-1 1][21] [y]=[5 -4][20] d) [x]=[1 1][21] [y]=[5 4][20] if there is any confusion on what anything written here is here is a screenshot of everything.

Valentino starts with a population of 1,500 amoebas that increases 35% in size every hour for a number of hours, h. the expression 1,500(1+0.35)h finds the number of amoebas after h hours. which statement about this expression is true? a. it is the initial population raised to the growth factor after h hours. b. it is the sum of the initial population and the percent increase. c. it is the sum of the initial population and the growth factor after h hours. d. it is the product of the initial population and the growth factor after h hours.

Name the most appropriate metric unit for each measurement

The number of chocolate chips in an 18-ounce bag of chocolate chip cookies is approximately normally distributed with a mean of 1252 chips and standard deviation 129 chips. (a) what is the probability that a randomly selected bag contains between 1100 and 1500 chocolate chips, inclusive? (b) what is the probability that a randomly selected bag contains fewer than 1125 chocolate chips? (c) what proportion of bags contains more than 1225 chocolate chips? (d) what is the percentile rank of a bag that contains 1425 chocolate chips?