SOLUTION: An office supply store in new york sells 7 tablets and 4 pens for $6.40. Also , two tablets and 19 pens cost $5.40. Find the price of each

Algebra ->  Problems-with-consecutive-odd-even-integers -> SOLUTION: An office supply store in new york sells 7 tablets and 4 pens for $6.40. Also , two tablets and 19 pens cost $5.40. Find the price of each      Log On


   

Question 826447: An office supply store in new york sells 7 tablets and 4 pens for $6.40. Also , two tablets and 19 pens cost $5.40. Find the price of each
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +a+ = the cost for 1 tablet in cents
Let +b+ = the cost of 1 pen in cents
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(1) +7a+%2B+4b+=+640+
(2) +2a+%2B+19b+=+540+ ( in cents )
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Multiply both sides of (1) by 2
Multiply both sides of (2) by +7+
Subtract (1) from (2)
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(2) +14a+%2B+133b+=+3780+
(1) +-14a+-+8b+=+-1280+
+125b+=+2500+
+b+=+20+
and, since
(1) +7a+%2B+4%2A20+=+640+
(1) +7a+=+640+-+80+
(1) +7a+=+560+
(1) +a+=+80+
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The price of a tablet is 80 cents
The price of a pen is 20 cents
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check:
(2) +2%2A80+%2B+19%2A20+=+540+
(2) +160+%2B+380+=+540+
(2) +540+=+540+
OK