Question 81569: please help.
The sum if two numbers is 35. Their difference is 13. what are the two numbers? Found 2 solutions by tutorcecilia, tutor_paul:Answer by tutorcecilia(2152) (Show Source):
You can put this solution on YOUR website! x=one number
y=the other number
sum=to add
difference=to subtract
.
x+y=35
x-y=12
.
One method you can use is subtraction;
x+y=35
x-y=12
_______
2x-0y=47
.
2x=47
x=47/2
.
So, x=47/2=23.5
x+y=35
23.5+y=35
y=35-23.5
y=11.5
checking: 23.5+11.5=35
.
Plug the values into the second equation:
x-y=12
23.5-11.5=12 [checks out]
You can put this solution on YOUR website! You are given two equations and two unknowns. Anytime you have at least as many equations as you have unknowns, you can solve the problem!
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Let the two numbers in question be called x and y.
From the given information we can say:
Equation #1:
and
Equation #2:
So, you have 2 equations and 2 unknowns. you are good to go.
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First, Solve Equation #2 for x in terms of y:
Now, substitute this expression for x into Equation #1 (that is why this is called the "substitution" method.
Solve for y:
Now, substitute this value for y back in to Equation #2:
Solve for x:
Check these answers by plugging the values back in to the original equations. They should both hold true.
Good Luck,
tutor_paul@yahoo.com
