SOLUTION: The sum of 2 times a first number and 4 times a second number is 78. If 1/2 the second number is subtracted from the first number, the result is 9. Find the number.

Question 1017325: The sum of 2 times a first number and 4 times a second number is 78. If 1/2 the second number is subtracted from the first number, the result is 9. Find the number.
Answer by Cromlix(4381) (Show Source): You can put this solution on YOUR website!
Hi there,
Make First number = x
Second number = y
The sum of 2 times a first number
and 4 times a second number is 78
If 1/2 the second number is subtracted
from the first number, the result is 9.
2x + 4y = 78........(1)
x - y/2 = 9.........(2)
Multiply (2) by 2
2x + 4y = 78........(1)
2x - y = 18.........(2)
Subtract (2) from (1)
5y = 60
y = 12
Substitute y = 12 into (1)
2x + 4y = 78
2x + 4(12) = 78
2x + 48 = 78
2x = 78 - 48
2x = 30
x = 15
First number = 15
Second number = 12
Hope this helps :-)
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