Answer:
-4z is the answer
Step-by-step explanation:
-3z-z
-4z
You have to use the y=mx+b formula to find the equation
Answer: 
This is the same as writing (n-m)/n
Don't forget about the parenthesis if you go with the second option.
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Explanation:
The probability that she wins is m/n, where m,n are placeholders for positive whole numbers.
For instance, m = 2 and n = 5 leads to m/n = 2/5. This would mean that out of n = 5 chances, she wins m = 2 times.
The probability of her not winning is 1 - (m/n). We subtract the probability of winning from 1 to get the probability of losing.
We could leave the answer like this, but your teacher says that the answer must be "in the form of a combined single fraction".
Doing a bit of algebra would have these steps

and now the expression is one single fraction.
You have to find the unit rate
SO..
7.70 / 154 = 0.05
So it cost her 0.05 cents for each text.
So then you divide $ 5.25 by the unit rate to get the number of text
5.25 /0.05 = 105
so she sent 105 text
To check it you just multiply the unit rate by the number of text you got and you show come up with $ 5.25
0.05 x 105 = 5.25
The answer would be -12+8i