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Solving Systems Equations by Substitution

 

Chris has $3.85 in dimes and quarters. There are 25 coins in all. How many of each type of coin does he have?

 Jul 21, 2020
 #1
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q = # quarters         value  = 25q

d = #dimes              value = 10d

 

q+ d = 25

25q + 10d = 385      from first equation   d = 25-q    use this in the second equation

 

25q  + 10(25-q) = 385         now you can solve for  q      then d   = 25-q

25q+250-10q = 385

15q= 135

q = 9   quarters       d = 25 - q = .......

 Jul 21, 2020

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