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Question 29682:  sum of two numbers is 42 and their difference is 30. find each of the numbers. 
 Answer by ikdeep(226)      (Show Source): 
You can  put this solution on YOUR website! Let the first number = x  
Let the second number = y 
 
According first condition i.e sum of two numbers is 42 ...we get 
 
x+y = 42............(1)
 
According second condition i.e difference of two numbers is 30 ...we get 
 
x-y = 30.............(2)
 
on adding (1)and (2)..we get...
 
 
x+y = 42 
x-y = 30 
-------- 
2x = 72 (+y and -y would be eliminated)
 
divide both side by 2 we get...
 
x = 72/2
 
x = 36
 
,,,to get the value of y, substitute the value of x either in (1) or in (2)...but here i took (1)....
 
x+y = 42............(1)
 
36 + y = 42
 
y = 42 - 36
 
y = 6 
 
so the values are x = 36 and y = 6......
 
To verify your answer you can put the value of x and y in either (1) or(2) 
or in both and you will always get LHS = RHS
 
please feel free to revert back for any further queries.
 
 
 
 
 
 
 
 
 
 
 
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