I don't know how to do percent of change

Answer 1

if you had 77 peanuts and increased that by 23 %
then you have 100% plus 23% = 123%
fraction = percent /100
so
multiply 77 by 1.23

If you had 77 and decreased by 23 %
that is 100% minus 23 % = 87%
so
multiply 77 by 0.87

The End.

Answer 2

or, going in reverse, if you had an amount of 52, which increased to 60, then
the raw change is 8
but the % change is 8/52 = 15.38%