Chemistry problem (isotope related)

A question asks me: "Assuming that Carbon has only one type of isotope (13C) estimate the mass and number of moles of 13C in 300g of carbon?"

How am I supposed to figure this out? Please show all working

It's a trick question. If Carbon had just one isotope of C13, than the average atomic mass would be 13 amu for any amount of carbon. The atomic mass of an element is the average masses of its isotopes. Here, we have just one making it the average mass. On a periodic table we have some elements that have only one known isotope in nature. For example Rn which is radon. Radon's atomic mass is 222 amu. It is shown as (222) because Rn222 is the only isotope in nature. The number of moles would be 300g/13g. Now that we have established the average atomic mass to be 13 amu we know that a mole of this fictional carbon would be 13g. So it turns out to be about 23.08 mol of C. Hope this helps.

i am tempted to do 300/13 to get the answer, but i am not sure what percent of this 300g carbon has carbon-13 in it, because this type of problem is usually involve with elemental decay.

No of moles =weight /mol.wt

so....300/13 =23.0769231 mol.