Step One
Find the cost of one bottle
12 bottles cost 9.25 pounds.
1 bottle costs x
12 / 1 = 9.25/x Cross multiply
12*x = 1 * 9.25 Divide by 12
x = 9.25 / 12
x = 0.77
Remark
0.77 pounds sterling = 77 pennies
Step Two
find the profit on the sale of one bottle
100 - 77 = 23 pennies
Step Three
Find the % profit on one bottle.
% Profit = (profit on one bottle / Cost of 1 bottle.) * 100%
% Profit = (23 / 77) * 100
% Profit = 29.87% <<<<<<<< Answer.