Question

A student has 12 coins, all dimes and quarters. The value of the coins is $1.95. How many dimes are there?

Answer 1

Define your variables, and solve a system of equations. You know that dimes + quarters = 12 and that the dimes * .10 plus quarters * .25 = 1.95. Now solve.

Answer 2

you have 2 equations in 2 unknowns that need to be solved simultaneously

let d = dimes and q = quarters

d + q = 12 total number of coins (1)
0.1d + 0.25q = 1.95 total value of the coins (2)


multiply equation (2) by 4 and subtract it from equation (1). This will eliminate q and allow you to solve for d

Answer 3

i am confused....

Answer 4

What part confuses you?

Answer 5

basically everything....

Answer 6

@campbell_st and I gave you the same answer, though worded slightly different. You are dealing with a system of equations and so you need to solve for one variable, substitute that into the other equation and solve for your second variable.
So given the multiple steps, which ones have you been able to work through?

Answer 7

if this system confuses you use trial and error...

start with 12 dimes.... what value do you have...?

if its not enough go to

11 dimes and 1 quarter........what value....

just repeat the process... you need to always have 12 coins...

Answer 8

your goal is to have $1.95

Answer 9

Given that your answer ends in a 5, you should already know that you have an odd number of quarters.

Answer 10

ok thx

Answer 11

OHHHHH so the answer is 7 dimes?

Answer 12

Add them up, do you get $1.95?