SOLUTION: Hello, I am working on a problemn that goes like this: The cost of a long-distance telephone call is $0.36 for the first minute and $0.21 for each additional minute or portion ther

Question 112921: Hello, I am working on a problemn that goes like this: The cost of a long-distance telephone call is $0.36 for the first minute and $0.21 for each additional minute or portion thereof. Write an inequality representing the number of minutes a person could talk without exceeding $3.
What I have for the inequality so far is this: x=0.36+0.21x=$3.00, am I even close on this?
Thank you for your help,
Barb Neely
Answer by ptaylor(2198) (Show Source): You can put this solution on YOUR website!
SEE IF YOU CAN FOLLOW MY APPROACH, BARB. I LIKE TO LAY OUT WORD PROBLEMS SO I CAN CLEARLY SEE WHAT THE UNKNOWNS REPRESENT AND HOW THEY RELATE TO OTHER COMPONENTS OF THE PROBLEM.
Let x=number of minutes a person can talk without exceeding $3.
Now we are told that the cost of talking x minutes=$0.36+0.21(x-1) and we are also told that this has to be less than or equal to $3. So our inequality is:
$0.36+$0.21(x-1)<=$3 get rid of parens
$0.36+$0.21x-$0.21<=$3 simplify
$0.15+$0.21x<=$3 subtract $0.15 from both sides
$0.15-$0.15+$0.21x<=$3-$0.15 collect like terms
$0.21x<=$2.85 divide both sides by $0.21
x<=13.5714 minutes but we would be charged for 14 minutes
14 minutes would cost $0.36+13*$0.21=$0.36+$2.73=$3.09 and this breaks the bank so we have to round down to the nearest minute:
x<=13 minutes---------ans
CK
$0.36+12*$0.21=$0.36+$2.52=$2.88 and
$2.88<=$3.00------------------one more minute or portion thereof would break the bank

Hope this helps---ptaylor

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