Question

Solve using a system of equations:
There is a collection of nickels and dimes worth $3.30. There are 42 coins in all. How many are there of each kind?

Answer 1

5n + 10d = 330
n + d = 42

Answer 2

n is the number of nickels and d is the number of dimes.

Answer 3

so you gotta use the second equation to solve for d

Answer 4

or n, but i would do d

Answer 5

so what does d equal?

Answer 6

D=576

Answer 7

no, what you gotta do it find out what d is compared to n.

so it's n + d = 42. what you do with that is subtract n from both sides to get d = 42 - n

Answer 8

and then you can substitute 42 - n for d in the first equation

Answer 9

so 5n + 10d = 330 would be 5n + 10(42 - n) = 330.

is this making sense?

Answer 10

Yes, but we have to have a system of equations

Answer 11

the first thing i posted was our system of equations

Answer 12

now we're solving it

Answer 13

Oh right sorry

Answer 14

so do you know what to do from there? from 5n + 10(42 - n) = 330?

Answer 15

ok

Answer 16

so just distribute and then solve from there?

Answer 17

yea, distribute the 10 into the parentheses and then solve for n and once you know how many nickels there are, just substitute that for n in the second equation and solve for d

Answer 18

i get a negative