please help me with this math question on my homework? and i need it for tomorrow?

Question

The ratio of Carls money to donalds money is 7:3 .
if carl gave donald $20, the two then have equal amounts.
find the origional amount that each one had.


if you could answer this for me thatd be great, and if you do please give details on how to do it, than you very much.

Answer 1

...the above answers are wrong because:

C-20 does not equal D. Carl loses 20 dollars, but Donald gains 20 dollars so C-20 = D+20.

STARTING OVER:

So you know that C/D = 7/3 and that (C-20)/(D+20) = 1/1, where C = Carl's money and D = Donald's Money

If you cross multiply the first equation and solve for a variable, let's say C, you get:

C/D = 7/3
3C = 7D
C = 7/3D

So now, you can cross multiply the second equation to get:

(C-20)/(D+20) = 1/1
C-20 = D+20 (add 20 to both sides)
C = D + 40

Now, we know that C also equals 7/3D, so you can substitute:

C = 7/3D = D + 40
7/3D = D + 40 Subtract D (or 3/3D) from both sides to get
7/3D - D = 40 or
4/3D = 40 multiply both sides by 3/4
(4/3)(3/4)D = 40(3/4) or
D = 30

If C = 7/3D and D = 30, then

C = (7/3)(30) = 70

so C:D = 70:30 = 7:3

C - 20 = 50; D + 20 = 50

so C = 70 and D = 30

hope this helps

Answer 2

7-3=4 so you devide 4/20 which is 5

then you know that each part = 5$

so you multiply 7*5 which is 35 and 3*5 which is 15

so carls is 35$ and donald is 15$

Answer 3

To set up a ratio, use fractions.
Call Carl's money C and Donald's money D.
So c/d = 7/3
We also know that c - 20 = d
now you substitute.
c = 7d/3
So 7d/3 -20 = d
7d-60 = 3d
4d = 60
d = 15
c-20 = 15
so
c= 35
:)