# Math help needed!

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• 01-26-2010, 12:26 PM
Sonicxtacy02
needless to say i still dont get it lol: i've got another slightly different formula i need help with. Same scenario only not dealing with percentages

X= ((160 * 2.5)-100) * 0.145

in the above function X = 43.5. I need to the solve an equation which gives me X but not "160"... so like this

43.5 = ((X * 2.5)-100) * 0.145

So how do i solve for X in that second equation
• 01-26-2010, 01:06 PM
Curiosity
Are you reversing the math? The easiest way to think about it is to break it down and reverse each basic equation.
X = n * 2.5 reversed is n = X / 2.5 and keep going...

A = 160 * 2.5
B = A - 100
X = B * 0.145

reverse...

D = X / 0.145
E = D + 100
F = E / 2.5

So now F = 160

Now put it all back together

X = ( (43.5 / 0.145) + 100 ) / 2.5
• 01-26-2010, 02:02 PM
Sonicxtacy02
well that took me awhile but now i get it. Thanks for the insight Curiosity!
• 01-27-2010, 02:32 PM
Maheriano
I used to just draw a triangle and put the three numbers inside. 1 number at the top and 2 numbers in the bottom corners. So say you have A at the top, B in the left corner and C in the right corner. You can visually see how the equation changes:
A = B * C
B = A / C
C = A / B
I used that for years.
• 01-28-2010, 09:42 AM
Sonicxtacy02
In college i majored in Business Admin AND Info technology. If i ever go back i'll major in mathematics lol. I always get caught up with this kinda stuff in my programming.
• 01-29-2010, 07:59 AM
nasa
It's been a while, but here's another way to go about solving equations (just in case it comes up again....)

First off somethings to remember:

1. Any changes you do to one side of an equation make sure you do it to the other
2. As long as you remember #1, reducing a term to 1 (when division or multiplication is at play) or 0 (for addition/subtraction) is a good thing.

Ok given the above and the starting equation [ 43.5 = ((X * 2.5)-100) * 0.145
] -- Let's apply these rules, remembering that we are solving for X:

step 1: 43.5 / 0.145 = ((X * 2.5)-100) * (0.145 / 0.145) [ dividing by 0.145 by 0.145 is 1 and since we did this on one side must apply it to the other]

step 2: (43.5/0.145) + 100 = x*2.5 - 100 + 100 [ adding 100 to -100 is 0, done on one side must be done on the other ]

step 3: ((43.5/0.145) + 100) / 2.5 = x [hopefully you follow by now....]

These steps would have helped in any of these type of equations.
• 02-05-2010, 06:45 PM
JohnsonBB
Quote:

Originally Posted by Maheriano
I used to just draw a triangle and put the three numbers inside. 1 number at the top and 2 numbers in the bottom corners. So say you have A at the top, B in the left corner and C in the right corner. You can visually see how the equation changes:
A = B * C
B = A / C
C = A / B
I used that for years.

Hopefully you found your answer, I don't have the level of math to resolve this.
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