Brand Z's annual sales are affected by the sales of related products X and Y as follows: Each $1 million increase in sales of brand X causes a $6.5 million decline in sales of brand Z, whereas each $2 million increase in sales of brand Y results in an increase of $23 million in sales of brand Z. Currently, brands X and Y are each selling $2 million per year, and brand Z is selling $68 million per year. Model the sales of brand Z using a linear function. (Let z = annual sales of Z (in millions of dollars), x = annual sales of X (in millions of dollars), and y = annual sales of Y (in millions of dollars).) z=?

there is only one way to arrange all the eight relative to each other because they are not distinct. we have

now there are nine places to place an (and not more than one in one place).   because we have four symbols, we need to choose four of these nine places to insert an . order does not matter because the are not distinct.

thus there are 1 · c(9,4) ways, or, if we calculate it,

thus there are 126 ways to form such "words."

i'm sorry, what's your question here?

the answer is b because it has ^2 and the rest do not.

step-by-step explanation:

answer: $53750

steps:

list the principal and interest after the n-th year:

n       principal   simple interest

1     12500     375

2     25000     750

3     37500     1125

4     50000     1500

sum: $50000     $3750

total at end of year 4: $53750