Respuesta :
There are 7 nickels and 13 dimes. Scratch that...actually...
We know that an unknown amount of dimes and nickles equal $1.45. Well, we know that a dime is worth 10 cent and a nickel is worth 5 cent. A combination of these values results in the $1.45.
So, using "x" to describe the number of dimes and "y" to describe the number of nickels, we can construct this equation:
.10x + .05x = 1.45
We know that the amount of dimes and nickels (x an y) equals 20.
So...
x+y = 20
Now we will do something called Substitution.
If we move the x to the other side of the equation, it now looks like
y = 20 - x
We can plug this into the first equation
.10x + .05 (20 - x) = 1.45
.05 times 20 equals 1 and .05 times -x is -.05x
Now we have .10x + 1 -.05x = 1.45
Since they have the same variable attached to them, we can simplify -.05x and .10x to get .05x .
We can also minus the 1 and take it to the other side of the equation, minusing it from 1.45 to get .45
Then, we can divide the .05 by .45 to get 9.
There we have 9 nickels.
If we plug this back into the equation x+y = 20, since we now know that y is 9, we now know that there are 11 dimes (11 dimes plus 9 nickels equals 20 coins)
