please tell me if this is correct:

1/4 + 4/5= 1 1/20 and 5/9+5/6= 1 7/18

thank you

Yes. Both are correct.

To check if the given calculations are correct, let's go through the steps.

For the first calculation:
1/4 + 4/5

To add these fractions, we need to have a common denominator. In this case, the common denominator is 20 since both 4 and 5 can divide evenly into it.

So, we rewrite the fractions with a common denominator:
1/4 becomes 5/20 (multiply numerator and denominator by 5)
4/5 remains as 4/5

Now we can add the fractions:
5/20 + 4/5 = (5 + 16)/20 = 21/20

We can see that the sum is not equal to 1 1/20, but rather 21/20 or 1 1/20.

For the second calculation:
5/9 + 5/6

Again, we need a common denominator to add these fractions. The least common multiple of 9 and 6 is 18.

So, we rewrite the fractions with a common denominator:
5/9 becomes 10/18 (multiply numerator and denominator by 2)
5/6 becomes 15/18 (multiply numerator and denominator by 3)

Now we can add the fractions:
10/18 + 15/18 = (10 + 15)/18 = 25/18

The sum is not 1 7/18, but rather 25/18.

In conclusion, the first sum is correct as 1 1/20, but the second sum is incorrect. It should be 25/18.