The two numbers are a and b
a + b = 50
a/4 + 2b/3 = 25
Plug b=50 - a into the 2nd equation:
a/4 + 2(50 - a)/3 = 25 // Multiply by 4*3 = 12
3a + 8(50 - a) = 300
3a + 400 - 8a = 300
-5a + 400 = 300 // - 400
-5a = - 100 // divide by -5
a=20
Because a + b = 50:
b = 30
2007-10-14 00:21:58
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answer #1
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answered by Amit Y 5
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Let the first number be x, so the second is (50-x), so:
x/4 + 2(50 - x)/3 = 25.........xly thro by 12:
3x + 8(50 - x) = 300, so
3x + 400 - 8x = 300, so
400 - 5x = 300,so
5x = 100, so
x = 20, and (50-20) = 30.
So the two numbers are 20 and 30.
Always try to get the original equation in terms of one unknown rather than two. It makes the subsequent calculations a lot easier, because you only have to solve one equation, not two simultaneous ones.
Hope this helps, Twiggy.
2007-10-14 07:28:21
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answer #2
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answered by Twiggy 7
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equation 1. x + y = 50
equation 2. x/4 + 2y/3 = 25
From eq. 1, you get x = 50 - y, and substituting this for x in eq 2, you get the following:
50-y/4 + 2y/3 = 25 which can be written as
150-3y+8y/12 = 25
150-3y+8y = 300
5y = 150 so y = 30
Therefore x = 20
2007-10-14 07:27:36
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answer #3
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answered by Simonizer1218 7
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x = 1st number, y = 2nd number
Values of y:
y = 50 - x
1/4x + 2/3y = 25
2/3y = 25 - 1/4x
y = (25 - 1/4x) / (2/3)
Value of x:
2/3(50 - x) = 25 - 1/4x
100/3 - 2/3x = 25 - 1/4x
100/3 - 75/3 = 8/12x - 3/12x
25/3 = 5/12x
x = 20
Value of y:
= 50 - 20
= 30
Answer: 1st no. is 20, the 2nd no. is 30.
Proof (sum of 25):
= (1/4 * 20) + (2/3 * 30)
= 5 + 20
= 25
2007-10-14 07:26:57
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answer #4
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answered by Jun Agruda 7
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Let first number be X
Let second number be Y
1/4 of X+ 2/3 of Y=25
X+Y=50
so you have got 2 equations, to find X and Y solve the 2 equations simultaneously
2007-10-14 07:17:12
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answer #5
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answered by red_devil07 2
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x + y = 50
x/4 + 2y/3 = 25
3x + 8y = 300
- 3x - 3y = - 150----ADD
5y = 150
y = 30
x = 20
2007-10-14 07:56:22
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answer #6
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answered by Como 7
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