Question 14937: The difference of two numbers is 18, and their sum is 90. find the two numbers.
Answer by bam878s(77)   (Show Source):
You can put this solution on YOUR website! let x,y be the two numbers.
Then, x-y=18 and x+y=90.
Solve the first equation for x.
x-y+y=18+y
x=18+y.
Now, plug this into the second equation.
x+y=(18+y)+y=90
18+2y=90.
Subtract 18 from both sides.
2y=72. Now divde both sides by 2.
y=36.
Now pluge this value into either of the orginal equations to solve for x.
x-y=x-36=18.
Add 36 to both sides to get
x=54.
so x=54 and y=36.
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