✔ 最佳答案
Ok the idea here with fractions with different denominators, is to change both denominators so that they are the same, which will then allow us to add or subtract fractions
We do this by observing the numbers which make up the two denominators and then choosing the lowest common factor.
In this case the numbers are 5 and 3. The lowest common factor here is 15.
We then multiply the bottom number to get 15, and then we multiply the top number by same number we did for the bottom number
for example, to make 5 into 15, we multiply by 3. We then would multiply the 9 on top by 3 too, to make the fraction equivalent to its simplist form (i.e. 9/5 = 27/15)
Therefore: 9/5 - 4/3
= 27/15 - 20/15
=7/15
Hope that helped :)