Answer:
75%
Explanation:
When we multiply a number by 1.75.
Now, note that:

Therefore, when we multiply a number by 1.75, it is the same as increasing by 75%.
Let us take an example say the number 15.
If we increase 15 by 75%, we have:
- 15+(0.75X 15)=15+11.25=26.25