If the cost of electricity increases by 30% by what percentage one should reduce his spend in order that spends on electricity stays the same?

That depend on how much you spend on electricity, and how much other spending you do.

For example: If your electric bill is 100 dollars, and it increases 30 percent to 130, that’s 30 extra dollars. If your electric bill is only 50 dollars, it will increase to 65, that’s an extra 15.

What percentage that increase is of your current spending will vary according to how much you spend. If you only spend 30 dollars, then you’ll need to cut all of it, or half of it to offset the increases I mentioned above. That’s a 100 percent or 50 percent reduction.

If you spend 1000 dollars, you’ll only need to cut spending by 3 percent to get that 30 dollars, or 1.5 percent to get the 15 dollars.

It all depends on your specific values, you can’t say “For every xx percent your electric bill increases, you need to cut spending by yy percent.”

for the consumption of X unit let u spends Y

for X - Y cost

for increased 30% means 13X/10 - 13Y/10 cost

extra money is 13Y/10 - Y = 3Y/10

note: hope this helps :)

thus (3Y/10)/ (13Y/10) *100 % = 300 / 13 = 23.07%.