Question 448793: A first number plus twice a second number is 8. Twice the first number, plus the second number totals 25. Find the numbers. Found 2 solutions by mananth, ikleyn:Answer by mananth(16949) (Show Source):
You can put this solution on YOUR website! x+2y=8 .............1
2x+y=25 .............2
Eliminate y
multiply (1)by 1
Multiply (2) by -2
1 x + 2 y = 8
-4 x + -2 y = -50
Add the two equations
-3 x = -42
/ -3
x=14
plug value of x in (1)
1x+2y=8
14+2y=8
2y=8-14
2y=-6
y=-3
You can put this solution on YOUR website! .
A first number plus twice a second number is 8. Twice the first number, plus the second number totals 25.
Find the numbers.
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There is very easy and effective way to solve it - practically mentally, in the head.
The equations are
x + 2y = 8 (1)
2x + y = 25 (2)
Add the equations
3x + 3y = 33,
hence
x + y = 11. (3).
Compare (1) and (3). It should be clear from the comparison that y = -3.
Next, compare equations (2) and (3). It should be clear for the comparison that x = 14.
Now check these values and makes sure that they satisfy equations.
