Maths Question

[HongKongphooey]

I have an net amount of 134.40 of which 20% has been already been taken off, how do i calculate the original gross amount?
Not sure if this the right section but there isn't a maths section!

[elliemay1]

divide by 8, then multiply by 10.

[bhg481]

If 20% has been taken off then 134.40 is 80% of the original. 134.40 x 100 / 80 will give you the original amount.

[sandyRoe]

£134.40 is 80% of the figure you need. Multiply by 5/4 to get the original sum. =£168.00

[elliemay1]

^ If 20% is taken off then you are left with 80% which equals £134.40. This is 8 tenths or 4 fifths.

[Old_Geezer]

Wot effie said.

The amount quoted is 80% so you can divided by 80 to know what 1% is.
The amount you wish to know is 100%, so next multiple by 100 to get the full amount.

Or divide by 0.8 then multiply by 1 (but you'll need to know your 1 times table for that).

[elliemay1]

^effie??

[HongKongphooey]

Doh... Thanks guys don't know what i'd do without you lot, shoulda paid more attention in my maths lessons...lol

[Old_Geezer]

Tech dislikes me and continually changes what I type. I clearly pressed the l key. This is one of the reasons I am so cheesed off at the lack of edit facility here. Once it is here it is here forever trying to make out I am some sort of moron. Folk should have the ability to return typing and posts to what they actually pressed.

[elliemay1]

^ It's okay, OG. Don't fret!

[Canary42]

I agree OG. I know the edit facility can, if misused, sometimes torpedo subsequent responses, but most forum sites offering an edit feature limit it to a fairly short time to overcome most such examples.

[tamborine]

Type in 134.40 into calculator, + 20% = 161.28

[Old_Geezer]

I think most folk have something that bugs them. Unintentionally looking a fool is something I cringe at. Doubt if I'll change now, not at my age.

[-SharonA-]

Two different replies here for the gross amount!!!!

[fiction-factory]

That would give the wrong answer though, tambo- you need to add 25% not 20%

[sandyRoe]

I did the sum in my head. Maybe I got it wrong

[elliemay1]

The first one is correct.

[Old_Geezer]

If you add 20% to the 80% you don't get 100%. Calculator doesn't know it was supposed to be 80%.

You will be adding it to a figure that has been taken to be 100% and will end up with 120% of it.

[tamborine]

Lol, knew I was wrong - ...king calculators

[elliemay1]

Tambo, you are adding on 20% of £134.40.

[mibn2cweus]

Gross minus (Gross times 0.2) equals
Gross times 0.8 equals
134.40

0.8 * G = 134.40
rearranged to solve for G
G = 134.40 / 0.8

Gross = 168