SOLUTION: a number minus twice another number is 4. Three times the first number plus two times the second number is 12. What are the numbers?

Question 830229: a number minus twice another number is 4. Three times the first number plus two times the second number is 12. What are the numbers?
Found 2 solutions by JulietG, TimothyLamb:
Answer by JulietG(1812) (Show Source): You can put this solution on YOUR website!
Let x be the first number, and y be the second number.
Here is the information that the question gives us:
x - 2y = 4 (a number minus twice another number is 4)
3x + 2y = 12 (three times the first number plus two times the second number is 12)
Add these together:
(x+3x) (-2y+2y cancel each other out) = 16
Add the Xs
4x = 16
Divide each side by 4
x = 4
.
If we know that x is 4, then we can use the information given to find y.
x (which is 4) - y = 4
4 - y = 4
y is therefore 0
.
Plug it in to prove it.
Three times the first number (3*4) + two times the second number (2*0) = 12
12 + 0 = 12
.
Tricky because of the 0. It misleads your thinking :-).
Answer by TimothyLamb(4379) (Show Source): You can put this solution on YOUR website!
---
x - 2y = 4
3x + 2y = 12
---
copy and paste the above linear system in standard form into this matrix-method solver:
https://sooeet.com/math/system-of-linear-equations-solver.php
---
solution:
x = 4
y = 0
---
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https://sooeet.com/math/linear-equation-solver.php
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https://sooeet.com/math/quadratic-formula-solver.php
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Solve systems of linear equations up to 6-equations 6-variables:
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