"how many will I need" formula

[Switcher]

I appreciate the help I am trying to write a formula and I am stuck on this point.
To try to keep it simple the equation I am working with is this
(A+B)/(A+B+C+D+E)=%

I am working this toward a goal % as the answer, where I am stuck is that I am trying to figure out a formula so I can see how many E will need to be added additionally to get to goal
EX:
(A+B)/(A+B+C+D+E)=15%
Goal being 10%
I will need 5 additional "E" to get to 10%
I want to plug this formula in a cell by itself so that it can easily be seen how many "E" are needed to get to goal.
Any help would be greatly appreciated. I know enough about formulas to get myself stuck.

I apologize I did not see anything in regards to cross posting links

here is the link to the other forum post, mrexcel.com/forum/excel-questions/1064621-how-many-will-i-need-formula.htm

[Special-K]

There's a plugin called Solver that helps this sort of problem but Ive never used it myself.

[63falcondude]

Hello and welcome to the forum.

Try this:

I put numbers in A1 through E1 then in B4 used this formula:
=(A1+B1)/(A1+B1+C1+D1+E1)

Data > What-If Analysis > Goal Seek > Set cell: B4 > To value: 0.1 > By changing cell: E1 > OK > OK

[63falcondude]

If you want to use Solver instead of Goal Seek, first you have to make sure that the Analysis Tool Pack is enabled (you can see how to do this online).

Then Data > Solver > Set Objective: B4 > To: Value Of: 0.1 > By Changing Variable Cells: E1 > Solve > OK

[Switcher]

I see that can change the result to 10%, it auto increases the amount, I apologize I must not have explained very well what end result I need
In the end I want to know how much of an increase is needed to go from current percentage to goal percentage
EX. current result is 15% goal being 10%, I need to increase the value in cell E by 8 to get to 10%
This value would then be displayed in a cell by itself
I hope that helps, explaining a cell formula is not my strong suit.

[AliGW]

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[Sam Capricci]

deleted d/t issue...
OOPs, while typing, didn't know about a cross post.

[Switcher]

I apologize I did not see anything in regards to cross posting links

here is the link to the other forum post, mrexcel.com/forum/excel-questions/1064621-how-many-will-i-need-formula.htm

I kept getting server errors for this forum so I posted in another.

[63falcondude]

See attachment. Same principal as post #3 but here we have a "Have" row and a "Want" row.

After running Goal Seek on the "Want" row, you can subtract the two E values to get how much you need (done in cell F6).

For this sample, these are the values to put into Goal Seek:
Set cell: H3
To value: 0.1
By changing cells: F3

[Switcher]

that did it thank you very much

[63falcondude]

You're welcome. Happy to help.

If that takes care of your original question, please select Thread Tools from the menu link above and mark this thread as SOLVED.