SOLUTION: 13.The cost of a pen is P12 more than the cost of the pencil. If the cost of 10 pencils and 8 pens is P339, find the cost of each.

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Question 659734: 13.The cost of a pen is P12 more than the cost of the pencil. If the cost of 10 pencils and 8 pens is P339, find the cost of each.
Answer by fcabanski(1391) About Me  (Show Source):
You can put this solution on YOUR website!
pen = pencil+12 and 10pencil +8pen = 339.


Two equations and two unknowns. Use the first equation to substitute the value of pen in terms of pencils into the second equation and solve it.


10pencil + 8(pencil+12) = 339


10pencil +8pencil + 96 = 339


18pencil = 243


pencil = 13.5


pen = pencil + 12 = 13.5+12 = 25.5