Algebra

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Scooby Scooby
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Algebra

I could only figure out part of the problem but have no idea how to progress.  Mice and cats together equal a total of 60, 3 times the number of mice exceeded cats by 20, what's the number of cats? Please help on the next step 3nm=nc+20,
nc+nm=60,
3nm-20+nm=60,  
?
AlgebraHouse AlgebraHouse
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Re: Algebra

Only use two variables, representing the number of mice and the number of cats.

m = number of mice
c = number of cats

m + c = 60   {mice and cats together equal a total of 60}
3m = c + 20   {three times the number of mice exceeded cats by 20}

m + c = 60   {first original equation, unchanged}
3m - c = 20   {subtracted c from each side of second equation}
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4m = 80   {added the two equations}
m = 20   {divided each side by 4}

m + c = 60   {first equation}
20 + c = 60   {substituted 20, in for m, into first equation}
c = 40   {subtracted 20 from each side}

40 cats

- Algebra House