Question 811707
{{{n}}}= number of nickels in {{{d}}} dollars
{{{5*n}}}= value of {{{n}}} nickels, in cents
{{{100*d}}}= value of {{{d}}} dollars, in cents
 
So the equation is {{{5*n=100*d}}}
because the value is the same.
Or you could write it as {{{n*5=100d}}} , or {{{5n=100d}}} .
 
Anyway, dividing both sides of the equal sign by 5,
you get equal amounts on both sides again, and you have
{{{5*n/5=100*d/5}}} which simplifies to {{{highlight(n=20d)}}}
That last equation allows you to calculate the amount of nickels in {{{d}}} dollars, and that is the answer to your problem.
 
No matter what {{{d}}} is, you just multiply that number of dollars times 20 and you get how many nickels that is.
You do not need to know algebra to figure that out, because you know that there are 20 nickels in a dollar.
The beauty of algebra is that if you know how to write a formula like that,
anyone who can read algebra can make the calculations for you for many different values.
If you can read algebra, you can work for an engineer calculating his (or her) formulas all day. It can pay nicely.
If you are the engineer, you write the formulas, and have other people (or a computer) do all the calculations for you, and the engineer gets paid even better.