Question 75285: Business and finance. The cost for a long-distance telephone call is $.036 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.
Please help I cannot figure this one out. Here is my inequality so far 36+21+x>3
Answer by ptaylor(2198)   (Show Source):
You can put this solution on YOUR website!
THE EQUALITY SIGN MUST BE A <= SIGN BECAUSE WE ARE TOLD THAT THE COST CAN'T EXCEED $3.00. AT LEAST YOU GAVE IT A SHOT BUT I'M NOT SURE THAT I CAN FOLLOW WHAT YOU DID. SEE WHAT YOU THINK ABOUT MY APPROACH:
FIRST, I'M ASSUMING YOU MEANT $0.36 AND NOT $0.036
Anyway, let's deal in pennies to make life more simple
Let x=number of minutes a person can talk without exceeding 300 (pennies)
First minute cost=36 cents
additional minutes cost 21 cents per minute
So our equation is:
36+21(x-1)<= 300 ----------------this is what I get (Note that I subtracted out the first minute)
36+21x-21 <=300
21x+15 <=300 subtract 15 from both sides
21x+15-15 <=300-15 collect like terms
21x <=285 divide both sides by 21
x<=13.5714 or 13 minutes (We can't round up because x is LESS THAN OR EQUAL TO 13.5714). Also, if you try 14, you will find that it breaks the bank.
ck
36 +12*21<=300
36+252<=300
288 <= 300 another minute would cost 21 cents--no can do!
Hope this helps----ptaylor
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