math question?

Question

jack has 57 coins, all of which are pennies or nickels. is it possible for him to have exactly $1.00?

Just wonerin took me a while to figure it out but i got it! how did you get your answer?

Answer 1

Let x = # of nickels

So 57 - x = # of pennies

Set up the equation:

5x + (57-x) = 100

4x + 57 = 100

4x = 43

x = 10.75 WTF!

OK we'll try it: (10.75 x 5) + (57-10.75) = 100!!

Since you can't have 10.75 nickels + 46.25 pennies it is impossible to have exactly 1 dollar.

You can check this: these are the two combinations that come the "closest" to 1 dollar.

(10 nickels x 5) + (57-10 pennies) = $0.97
(11 nickels x 5) + (57-11 pennies) = $1.01

Answer 2

Set it up as a two variable system of equations............

Let n=number of nickels and d=number of dimes
n+d=57
.05n+.10d=1.00

Solve by substitution, one variable at a time. (hint: n=57-d)

Plug that into the second one, which gives you the value of one variable, solve for the second.