Question 1201892
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Miguel the trainer has two solo workout plans that he offers his clients: Plan A and Plan B. 
Each client does either one or the other (not both). 
On Monday there were 4 clients who did Plan A and 8 who did Plan B. 
On Tuesday there were 2 clients who did Plan A and 3 who did Plan B. 
Miguel trained his Monday clients for a total of 9 hours and his Tuesday clients for a total of 4 hours. 
How long does each of the workout plans last?
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<pre>
Let x = hours for plan A and y = hours for plane B.

Write equations as you read the problem

    4x + 8y = 9     (1)   (total hours on Monday)
    2x + 3y = 4     (2)   (total hours on Thursday)  


To solve this system, multiply equation (2) by 2 (both sides).
Keep equation (1) as is.  You will get

    4x + 8y = 9     (3)   
    4x + 6y = 8     (4)  


Now subtract equation (4) from equation (3), The terms with "4x" will cancel each other,
and you will get

         8y - 6y = 9 - 8

            2y   =   1

             y   = 1/2 = 0.5.


Then from equation (2)

    2x + 3*0.5 = 4,

    2x + 1.5   = 4

    2x         = 4 - 1.5 = 2.5

     x                   = 2.5/2 = 1.25.


<U>ANSWER</U>.  Plan A is 1.25 hours per client (same as 1 hour and 15 minutes).

         Plan B is 0.5  hours per client (same as 30 minutes).
</pre>

Solved.


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On the way, you learned on how the Elimination method works, 
when you solve systems of two equations in two unknowns.



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Notice that the way on how tutor @Theo introduces his unknown variables may perplex/confuse you.


Surely, x and y in his post are not the numbers of clients;  
they are the hours per a client for plan A and plane B, respectively.


Precisely as they are introduced in my solution.