12. what's the simplified form of x − 1 + 4 + 7x − 3?
a. 6x
b. 8x
c. 8x + 6
d. 6x + 3
19. simplify and solve this equation: 4m + 9 + 5m – 12 = 42.
a. m = –5
b. m = -4
c. m = 4
d. m = 5
i'm really bad at simplifying

Amachine that produces a special type of transistor (a component of computers) has a 2% defective rate. the production is considered a random process where each transistor is independent of the others. (a) what is the probability that the 10th transistor produced is the first with a defect? (b) what is the probability that the machine produces no defective transistors in a batch of 100? (c) on average, how many transistors would you expect to be produced before the first with a defect? what is the standard deviation? (d) another machine that also produces transistors has a 5% defective rate where each transistor is produced independent of the others. on average how many transistors would you expect to be produced with this machine before the first with a defect? what is the standard deviation? (e) based on your answers to parts (c) and (d), how does increasing the probability of an event a↵ect the mean and standard deviation of the wait time until success?