The information we have is:
Soap used in 1/2 day is 3/4 of a bottle.
We need to find how much soup would be used in a full day.
Since a full day is double of 1/2 day, we need to multiply the given information by 2.
Multiplying the amount of soap by 2:

When we multiply a number by a fraction, we multiply that number by the numerator:

Solving these operations:

Converting this to a mixed fraction:

Which is the same as:

Answer:
1 1/2