Your piggy bank has a total of 41 coins in it; some are dimes and some are nickels. If you have a total of $3.45, how many nickels do you have?

Question

sasogeek · Answer

i don't know the value of nickles or dimes in the US currency, sorry

anonymous · Answer

nickels are .05
dimes are .10

sasogeek · Answer

let number of nickels = x
let number of dimes = y

y+x=41
0.05x + 0.1y=3.45

can u solve simultaneous equations?

anonymous · Answer

15?

sasogeek · Answer

multiply the second equation by 10, you'll have
0.5x+y=34.5


now subtract your new equation from the first equation
     x + y =  41
0.5x + y =34.5
.......................            remember that you're subtracting
0.5x +0 = 6.5


this implies that x=6.5/0.5
x=13


if we substitute the value of x into our first equation
x+y=41
13+y=41
y=41-13
y=28


so you had 28 dimes and 13 nickels