SOLUTION: If 3(4x+5š›‘)=P, in terms of P what is the value of 6(6x+10š›‘)?

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Question 1172847: If 3(4x+5š›‘)=P, in terms of P what is the value of 6(6x+10š›‘)?

Found 2 solutions by Edwin McCravy, ikleyn:
Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
If 3(4x+5š›‘)=P, in terms of P what is the value of 6(6x+10š›‘)?

After distributing, the above asks:

If 12x+15š›‘=P, in terms of P what is the value of  36x+60š›‘?

Let k and m be such that:

36x + 60š›‘ = kP + mš›‘ 
36x + 60š›‘ = k(12x+15š›‘) + mš›‘
36x + 60š›‘ = 12kx + 15kš›‘ + mš›‘

We set coefficients of x equal:

36 = 12k
 3 = k

We set constants equal

60š›‘ = 15kš›‘ + mš›‘
 60 = 15k + m
 60 = 15(3) + m
 60 = 45 + m
 15 = m

so  

36x + 60š›‘ = kP + mš›‘ = 3P + 15š›‘

or

6(6x+10š›‘) = 3P + 15š›‘   <--answer 

Edwin

Answer by ikleyn(52784) About Me  (Show Source):
You can put this solution on YOUR website!
.

We are given  3%2A%284x+%2B+5pi%29 = P.


It is the same as  12x+%2B+15pi = P.   (1)



Then  6%2A%286x%2B+10pi%29 = 36x + 60pi = regroup = 36x + 45pi + 15pi = 3%2A%2812x+%2B+15pi%29 + 15pi = 


    Now I replace  %2812x+%2B+15pi%29  by  P,  based on (1), and continue the chain of equalities in this way


    = 3P+%2B+15pi.    Completed.



ANSWER.   Then  6%2A%286x+%2B+10pi%29 = 3P+%2B+15pi.

Solved.

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In short terms,  I did  THIS:

    From the expression, which is under the question, I extracted the part, proportional to the given expression.


    Then I replaced this extracted part by the given value (symbol P, in this case).  The remaining addend was simply some constant.

That's  all.   It is small trick :),  actually - - - to learn for beginners.