correct answer is: a) 3

Explanation

Let the number which must be subtract is 'x'
According to the question,
\left(17-x\right):\left(33-x\right)=7:15
\rightarrow\large\frac{17\ -\ x}{33\ -\ x}\ =\ \frac{7}{15}
\rightarrow 15\left(17-x\right)\ =\ 7\left(33-x\right) _{[cross multiply]}
\rightarrow 255\ -\ 15x\ =\ 231\ -7x
\rightarrow -15x\ +7x\ =\ 231-255 _{[interchange]}
\rightarrow -8x\ =\ -24
\rightarrow\ x\ =\ \large\frac{-24}{-8}
\rightarrow\ x\ = 3
So, the number is 3 which must be subtracted from each term of the ratio 17 : 33 so that the ratio becomes 7 : 15.
Ans: The number is 3.

There’s another way to pose this same math question:

1. What subtraction is necessary from each term of the ratio 17:33 to convert it to the ratio 7:15?
2. How to modify the ratio 17:33 to become 7:15 by subtracting from each term?
3. Finding the subtraction value needed to change the ratio 17:33 to 7:15 without altering its proportion.
4. How to adjust the ratio 17:33 to 7:15 by subtracting a certain number from each term?