You need to ensure the denominators are the same. To do this you multiply the denominators together.
1/90 + 2/90
However, this is incorrect, as you need to do the same to the numerators, so for the left hand side you multiplied by 9 and for the right hand side you multiplied by 10, so you must do the same for the numerators.
So it should be:
9/90 + 20/90
You can now add this together, to get:
29/90
This is triple checked so I’m not sure why it says reduce the answer fully as that is as far as it can be reduced.
