I have twice as many quarters as dimes in his coin collection.  If the dimes and quarters together total 9 dollars, how man of each kind of coin do i have?

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Michelle -Simply take the words and put them into formulas.First let's call quarters Q and dimes D.Now, the first sentence says you have twice as many quarters as dimes.  In algebra this is written:Q = 2D.  Make sense?  Test it! If you have one dime then you have Q=2D or 2(1) = 2 quarters.Next sentence says the dimes and quarters add up to $9.  Again, in algebra this is stated as:$0.10D + $0.25Q = $9.00.  That is, every dime is worth 10cents and every quarter is worth 25cents.Now, you have two equations with two variables:Q = 2D$0.10D + $0.25Q = $9.00Now all you have to do is solve using your favorite method - substitution or elimination.  Looks like substitution will work great here!Hope this helped