Question

How they had got 30,18,45 and 10 how I had not understood ​

Answer 1

It's called taking L.C.M.

Here we are making the denominator same for all terms that's why we are dividing and multiplying with a number.

for example

1/2, 1/3, 1/5

I have to find greatest number

we'll take LCM for 2, 3 and 5

So LCM is a number which is perfectly divisible by 2, 3 and 5 , in this case we have 30.

1/2 × 15/15 = 15/30

1/3 × 10/10 = 10/30

1/5 × 6/6 = 6/30

So the greatest number is = 15/30.

before arranging the numbers, we have to make the denominator same by this technique.