Question 983046
Al,Bill and Carl went shopping.
When they compared the totals that each had spent they found that:
 Al and Bill together spent a total of Php 1200;
a + b = 1200
 Bill and Carl together spent a total of Php 1800.00;
b + c = 1800 
 and Al and Carl together spent a total of Php 1000.
a + c = 1000
How much did each person spend?
:
use elimination on the 1st two equations
0 + b + c = 1800
a + b + 0 = 1200
-------------------Subtraction eliminates b
-a + 0 + c = 600
c = (a+600)
In the 3rd equation; a + c = 1000, replace c with (a+600)
a + (a+600) = 1000
2a = 1000 - 600
2a = 400
a = 400/2
a = 200
find c using equation c = a + 600
c = 200 + 600
c = 800
Find b using the 2nd equation, replace c with 800
b + 800 = 1800
b = 1800 - 800
b = 1000
:
We have:
 Al spent 200
 Bill spent 1000
 Carl spent 800
:
you can check and see if all this adds up