Pay no attention to the man behind the curtain . . .
An energy-conscious homeowner makes three successive improvements
that save, in turn, 21%, 25% and 55% on the heating costs of the house.
The overall percentage saved is
The savings are: 21%, 25% and 55% of his heating bill.
This means that he pays: 79%, 75% and 45% of his heating bill.
. . That is, he pays: . of his heating bill.
EDIT (by Jhevon): so what percentage do you think he has saved?