Question 178706

WE CAN WORK THIS PROBLEM EITHER USING ONE EQUATION AND ONE UNKNOWN OR TWO EQUATIONS AND TWO UNKNOWNS. WE'LL SOLVE IT BOTH WAYS:
One unknown:
Let x=number of nickels
Then 70-x=number of dimes
Let's deal in pennies
5x=value of nickels
10(70-x)=700-10x=value of dimes
We are told that the above amounts add up to 485, so:
5x+700-10x=485  subtract 700 from each side
5x-10x+700-700=485-700  collect like terms
-5x=-215  divide each side by -5
x=43-------------------------------number of nickels
70-x=70-43=27--------------------------number of dimes

CK
43+27=70
70=70
and
5*43+10*27=485
215+270=485
485=485

Two unknowns:

Let x=number of nickels
And y=number of dimes
x+y=70------------------------------eq1
5x+10y=485--------------------------eq2
From eq1, y=70-x.  Substitute this into eq2

5x+10(70-x)=485-----------------------same equation as before


Does this help???-------------ptaylor