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21-06-2021
Mathematics

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7 pens and 2 pencils cost £22
3 pens and 4 pencils cost £11
find the cost of a pen:
find the cost of a pencil:

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21-06-2021

Answer:

Let pens be x and y be pencils

Let's solve now

7x+2y=22 equation 1

3x+4y=11 equation 2

let's make y the subject of the formular in equatio 1

y=(22-7x)/2

substituting y into the second equation yield

3x+4(22/2-7x/2)=11

Now find x.

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