x . . . .1
--- = ---
8 . . . .5
If you know how to do this, maybe you could explain. My 14 year old boy does not know how to do these. Thanks!
2007-09-06 08:47:49 · 9 answers · asked by brady s 1 in Science & Mathematics ➔ Mathematics
x / 8 = 1 / 5
(8) (x / 8) = (8) (1 / 5)
x = 8 / 5
2007-09-09 23:20:20 · answer #1 · answered by Como 7 · 1⤊ 0⤋
All you have to do is cross-multiply and then solve for x algebraically.
If you were to multiply both sides by 8 and both sides by 5, you'd get:
(x/8)(8*5) = (1/5)(8*5) on the left, the 8s will cancel out, and on the right, the 5s will cancel out...so essentially this is the same as taking the bottom numbers and multiplying them diagonally across...whichever method you use (long or short) you end up with:
5*x = 8*1 or
5x = 8
divide both sides by 5 to get
x = 8/5
To prove it's true, plug in 8/5 for x giving you:
(8/5)/8 = 1/5 which is the same as
(8/5)/(8/1) = 1/5 to divide (8/5) by (8/1) just flip the divisor (8/1) over and multiply giving you:
(8/5)/(8/1) = (8/5)*(1/8) = 1/5 notice how the 8's cancel out leaving you with;
(1/5) = (1/5)
Since this is true, we know we've found the right value of x.
2007-09-06 15:58:44 · answer #2 · answered by Matics101 6 · 0⤊ 0⤋
Take the Numerators time the opposite Denominators
(X*5 = 8*1) which can be re-written at 5X = 8.
To get rid of the 5 in front of the X divide both sides by 5.
you get X = 8/5
X=1.6
To check ourselves.
1.6 / 8 = 0.2
1 / 5 = 0.2
2007-09-06 16:01:00 · answer #3 · answered by Tony H 1 · 0⤊ 0⤋
Cross multiplication:
Multiply the top of the left had side by the bottom of the right hand side. Multiply the bottom of the left hand side by the top of the right hand side. Set these equal to each other and solve for x.
(x)(5) = (8)(1)
5x =8
x = 8/5
2007-09-06 15:53:31 · answer #4 · answered by T 5 · 0⤊ 0⤋
x / 8 = 1 / 5
Multiply both sides by 8 to get rid of the denominator on left
(x / 8) (8 / 1) = (1 / 5)(8 /1)
The 8's cancel on left to just the 'x' : (1)(8) / (5)(1) = 8 / 5
x = 8 / 5
2007-09-06 15:57:05 · answer #5 · answered by Don E Knows 6 · 0⤊ 1⤋
x/8 = 1/5
Multiply through by 8, and we have
x = 1 x 8/5
x =8/5
Convert to mixed fraction
x = 1 3/5
2007-09-06 15:56:54 · answer #6 · answered by lenpol7 7 · 0⤊ 1⤋
eliminate denominators -- multiply both by 8 and 5:
5x = 8, and x = 8/5
2007-09-06 15:52:53 · answer #7 · answered by John V 6 · 0⤊ 1⤋
ok so:
x/8 = 1/5
This is solvable using the law of '3 simple'...
So you simply cross multiply (so x * 5 = 1 * 8)
Therefore 5x=8
and x=8/5
2007-09-06 15:54:42 · answer #8 · answered by Anonymous · 0⤊ 1⤋
Formula to solve this question is :
suppose
x . . . .a
--- = --- a,b,c are known numbers
b . . . .c
x = a * b / c
so your answer is : x = 8 / 5 =1.6
2007-09-06 15:55:15 · answer #9 · answered by Nima J 4 · 0⤊ 1⤋