Carol buys a science textbook and a novel for English. She pays $138 to buy both books. The price of the science textbook is $3 less than 4 times the price of the novel. How much did each book cost?

What basic trigonometric identity would you use to verify that sin x cos x tan x =1-cos^(2)x?

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?

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?