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When Carly does 15 push-ups and 10 sit-ups, it takes a total of 35 seconds. In comparison, she needs 57 seconds to do 19 push-ups and 19 sit-ups. How long does it take Carly to do each kind of exercise.

 Feb 3, 2020
 #1
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15 p  + 10 s = 35

19 p + 19  s = 57        Simultaneous equations....2 unknowns    2 equations 

 

Mutiply eq 1 by    - 1.9

 

-28.5 p  - 19 s = -66.5    add to second equation

-9.5 p = -9.5

p = 1 second

      then YOU should be able to calculate  how long a sit up takes !   cheeky

 Feb 3, 2020

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