How do I calculate a percentage increase from a minus number?

Help!

I need to calculate the percentage increase from -3 to +15 and I just cant figure it out



Does anyone know??How do I calculate a percentage increase from a minus number?
Sorry but the question makes no sense. If -3 is the starting point of



-3=100%



then increasing it by say 100% would take it to -6.



Any percentage increase will make it a larger negative number.



If however you take away 100% you end up with zero. If you then remove another 500% you end up with 15. So you could say you decreased it by 600%. But this is all assuming in the first place that you mean that -3 is 100%.



MartinHow do I calculate a percentage increase from a minus number?
Since the sign is changing, this must be a negative percentage.



First, ignore the signs to make the change from 3 to 15

The difference is then 15-3 = 12 = 4*3 = 400%



But it needs to be negative, so -400%How do I calculate a percentage increase from a minus number?
each time you add 3 its 100% higher. To get from -3 to 15 that's 6 x 3 or 600%