# Math Help - percentages and reversing them

1. ## percentages and reversing them

hi,
how can i do this...

i did this...

10x0.8=8

then to reverse it i tied this

8x1.2=9.6

so how can i undo both of these to get back to 10?

thanks

2. Originally Posted by benhathaway
hi,
how can i do this...

i did this...

10x0.8=8

then to reverse it i tied this

8x1.2=9.6

so how can i undo both of these to get back to 10?

thanks
Hello,

the reciprocal value of 0.8 is 1.25:

$\frac{1}{0.8} = 1.25$

and

$8 \cdot 1.25 = 10$

3. this is for a shopping cart and i reduced all my items by 20% using the price x 0.8. Then i tried to make it back up by doing this price x 1.2. But this didnt work so how can get the original price back?

4. Originally Posted by benhathaway
this is for a shopping cart and i reduced all my items by 20% using the price x 0.8. Then i tried to make it back up by doing this price x 1.2. But this didnt work so how can get the original price back?
As earboth showed, you must multiply it by 1.25 (1 / 0.8)

5. hi,
the only problem is that i have the price that has allready been discounted by 20% and multiplied by 1.2. This cannot be reversed! Now i have tried to multiply by 1.25 so i need to reverse this...

price x 0.8 x 1.2 x 1.25

Thanks

6. Originally Posted by benhathaway
hi,
the only problem is that i have the price that has allready been discounted by 20% and multiplied by 1.2. This cannot be reversed! Now i have tried to multiply by 1.25 so i need to reverse this...

price x 0.8 x 1.2 x 1.25

Thanks
You want the price back to normal?

.8*1.2*1.25*y = 1
1.2y=1
y=.8333 OR 5/6