please help with simple math? please please?!?

Question

please!!! okay... Wendy has a collection of dimes and quarters that total $3.55. There are 25 coins in all. How many dimes and how many quarters are there? please help me!!! ive tried many solutions and cant get it! im really confused. thanks soo much!

plug WHAt in??? that didn't help so much. it sounded like my teacher. =[ mann.. im getting angry.. this is confusing. =[

Answer 1

Let d = # of dimes and q = # of quarters.

Since there are 25 coins, it follows that

d + q = 25

Since they total $3.55, it follows that

(0.10)d + (0.25)q = 3.55

Two equations, two unknowns. d + q = 25, so d = 25 - q.
Replace d = 25 - q for d in the above equation.

(0.10)(25 - q) + (0.25)q = 3.55

To get rid of all decimals, multiply both sides by 100.

10(25 - q) + 25q = 355

Distribute the 10.

250 - 10q + 25q = 355

Move the 250 over to the right hand side.

-10q + 25q = 355 - 250

Group like terms.

15q = 105

Divide both sides by 15.

q = 7

Which tells us there are 7 quarters. To get dimes,
d = 25 - q (by the above substitution), so d = 18.

18 dimes, 7 quarters.

Let's check:

18 dimes = $1.80

7 quarters = 7 x (0.25) = $1.75

$1.80 + $1.75 = $3.55

Answer 2

Okay, let's use a system of equations to find this out.

First, the equation for the amount of dimes and quarters:

d+q=25

Then for the monetary amount of the dimes and quarters:

.10d+.25q=3.55

As you know, dimes=.10 (or .1) and quarters= .25

Now list the equations vertically:

d+q=25
.1d+.25q=3.55

Now, use the substitution method and solve the first equation for, let's say, d. So, d= 25-q

Substitute d=25-q into the second equation.

.1(25-q)+.25q=3.55 Now solve for q

2.5-.1q+.25q=3.55 Combine like terms

2.5+.15q=3.55 Subtract 2.5 from both sides

.15q= 1.05 Divide

q=7 So there are 7 quarters. Now substitute this value in the first equation to get the amount of dimes.

d+q=25

d+7=25

d=18

Now to check our work:

18+7=25 Checks!
.1(18)+.25(7)=3.55
1.8+1.75=3.55
3.55=3.55 Checks!

So there are 7 quarters and 18 dimes.

Answer 3

Let the no of dimes be x,So the no of quarters is 25-x
The value of x dimes is x*10 cents=$0.10x
The value of 25-x quarters is 25(25-x)cents or $0.25(25-x)
=$6.25-0.25x
By the problem
0.10x+6.25-0,25x=3.55
=> -0.15x=3.55-6.25=-2.70
x=-2.70/-0.15=18
You can solve this problem in a very easy arithmatical way without the help of equation.
If all the 25 coins were dimes,the total value would be $2.50
But that is $1.05 less than the actual value given in the problem.
This has happened becausethere were some quarters also in the coins
Diff. of value in a quarter and a dime=$0.15
Therefore the no. of quarters is$1.05/$0.15=7
and the no of dimes is25-7=18
Therefore,no. of dimes =18
No. of quarters=25-18=7

Answer 4

dimes=y
quarters =x

x+y=25
x=25-y

.1y+.25x=3.55
.1y+.25(25-y)=3.55
-.15y+6.25=3.55
.15y=2.70
y=18
18+x=25
x=7
... 18 dimes 7 quarters....

Answer 5

okay so
x=dimes
y=quarters

x+y= 25
.1x+.25y =3.55

then just plug it in