Question 1190592
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on monday, revlien paid 66 pesos for 3 doughnuts and 2 cups of coffee. 
on tuesday, she paid 69 pesos for 2 doughnuts and 3 cups of coffee. 
how much did he pay for 1 doughnut and 1 cup of coffee on a wednesday?
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            This problem is intended for mental solution.



<pre>
Add her purchases on Monday and Tuesday:


    she bought 3+2 = 5 doughnuts and 2+3 = 5 cups of coffee, in total,

    spending 66 + 69 = 135 pesos.


HENCE, one doughnut and one cup of coffee cost  1/5  of it, i.e.  135/5 = 27 pesos.   


<U>ANSWER</U>.  On Wednesday, she must pay 27 pesos.
</pre>

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Solved.


Notice that I did not solve any systems of equations.


I even did not write them.



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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;using equations, &nbsp;but actually &nbsp;MUST &nbsp;be solved mentally.


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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;It is what the teachers expect to get from their students,

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;when they give them such problems.



&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;It is what the interviewers expect to get from the candidates

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;when they interview them somewhere in &nbsp;Microsoft or &nbsp;Google.



&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;But the final goal of teachers, &nbsp;when they give such problems, &nbsp;is to develop

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;the student's mind &nbsp;FLEXIBLE &nbsp;and &nbsp;CREATIVE, &nbsp;instead of making it dogmatic.