3 people divide $30 charge. They get refund of 1 dollar each and cashier keeps 2 dollars. When cross checking you multiply 9x3=27 plus 2 cashier kept equals $29. Where's the one dollar missing from the 30?

First, 3 people divide $30, then each one of them pays:

$30/3 = $10.

Each one of them gets $1 in refound.

Then at the moment, each one of them paid $9, and there are 3 friends, so the total amount is 3*$9 = $27.

We also know that the cashier keeps $2, but these $2 must come from the $27 that the friends paid.

Then we will have $27 = $25 + $2.

This means that the total cost was $25, and the cashier kept $2 as a tip.

Now, in your problem, you add the $2 that the cashier kept to the $27 that the friends paid. While those $2 actually are already counted in the $27 that the friends paid.

the function makes a strait line horizontally with no x intercept but a y intercept at 9.

step-by-step explanation:

to find if any function is an inverse of the other, put the first equation in as x in the next one. then simplify and solve. if at the end you get the statement y = x, then it is an inverse. if you get anything else, it is not.