SOLUTION: Hi the total cost of 20pens and 8 rulers is 32 dollars. Find the cost of 25pens and 10 rulers. thanks

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Question 1114775: Hi
the total cost of 20pens and 8 rulers is 32 dollars.
Find the cost of 25pens and 10 rulers.
thanks
Found 2 solutions by jim_thompson5910, ikleyn:
Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!
The statement "20pens and 8 rulers is 32 dollars" forms the equation 20p+8r = 32 where
p = cost of one pen
r = cost of one ruler

We don't have enough information to figure out how much 25 pens and 10 rulers will cost. We would need another statement similar to the first statement given.

So this problem cannot be answered in its current form. The general rule is that if you have two variables, then you need two equations. Similarly, if you have three variables, you'll need three equations, and so on.
Answer by ikleyn(52857)   (Show Source): You can put this solution on YOUR website!
.
20p + 8r = 32   dollars.


Divide by 4 both sides:


5p + 2r = 8   dollars.


Multiply by 5 both sides:


25p + 10r = 40  dollars.


Answer.  25 pens and 10 rulers cost 40 dollars.

Solved.

-----------------

The lesson to learn from this solution: 

    You do not need solving the system of equations in this case.

    You  simply need to multiply the given data by the factor of  .

    That is ALL the problem wants of you.



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