
Hey there!
I believe there's a typo here that makes 1/5 look like 15. If not, none of them are correct.
Assuming 15 is 1/5..
Let's start with our keywords:
Is means equals. (i.e he is good means he = good).
Of means multiplication (1/5 of 20 is 1/5 times 20 with is 20/5 is four).
This means that when reading this question, we have three less than whatever is next. 3 will be subtracted from the value listed next.
This value is 1/5 of a number. This means that we're multiplying 1/5 times this number, which we can call n.
We have to remember we are subtracting three and it all equals 28, which gives us:
1/5n - 3 = 28
Your answer is the 3rd option.
Hope this helps!