is 13/52 in simplest form

Yes it is in its simplest form

I don't understand what's in 1, 2, 3 ...

Are you looking for their product in lowest form?

if so ... then ...

1) 13/52 * 3/51 = 1/4 * 1/17

= 1/68 answer

2) 5/2 * 3/4 = 15/8 answer

3) 1/15 * 30/9 = 1/15 * 10/3

= 10/45

= 2/9 answer

Do you find converting to simplest form difficult?

Lets try #3 ...

a number with 1 on its numerator is already on its simplest form such as 1/15 ... with this all fraction must at least have numerator equal to 1 to say that it is in simplest form.

30/9 is not on in simplest ... think of a # that if you divide on both numerator and denominator will give a whole # ... ? Say you had in mind of 2 then try it, will it give a quotient of whole #? Lets try ... 30/2 = 15 which is whole #, and 9/2 = 4.5 which is not ... so 2 is wrong ...

Lets try 3 as divisor ...

30/3 = 10 which is whole #

9/3 = 3 which is whole # then the lowest term is the quotient we got which is 10/3. This is the lowest bec we cant think anymore # which if use as divisor will give whole # ...

another thing, multiplying two fraction on its lowest form doesn't mean it will give a product at its lowest ... just like in #3 ...