Lesson Using 1 variable as well as using 2 variables(substitution method)

Source code of 'Using 1 variable as well as using 2 variables(substitution method)'

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If a person has three times as many quarters as dimes and the total amount of money is 5.95, find the number of quarters and dimes.

*******************Using 1 variable:************************

Let the number of dimes = x
The value of dimes=10x
The number of quarters= 3x
The value of quarters= 3(25x)
The total amt of money= 5.95
Convert to cents=5.95*100=595 cents 
(1 Dollar=100 cents)

{{{10x+3(25x)=595}}}
{{{85x=595}}}
{{{x=7}}}

The number of dimes=7
The number of quarters= 7*3=21

************************Using Substitution Method:*******************

Let the number of dimes=d
The number of quarters=q
We know that the quarters are 3 times the dimes
So  {{{q=3d}}}

The value of quarters=25q
The value of dimes= 10d
The total amount of money is 5.95
Convert it to cents =5.95*100=595
(1 Dollar = 100cents)
{{{25q+10d=595}}}
substitute q with 3d in the above equation ***(as we know that q=3d)***
{{{25(3d)+10d=595}}}
{{{75d+10d=595}}}
{{{85d=595}}}
{{{d=7}}}

So number of dimes=7.
number of Quarters=3*7=21.