To sum these, first express each with the same denominator. This is easy to do once we notice that 34 is twice 17, so the fraction -3/17 can be written as -6/34. Now the sum becomes 9/34 - 6/34, or (9-6)/34, or 3/34.
I guess I should also note that adding a negative number just means subtracting that number, so 9/34 + (-3/17) is the same as 9/34 - (3/17)
To sum these, first express each with the same denominator. This is easy to do once we notice that 34 is twice 17, so the fraction -3/17 can be written as -6/34. Now the sum becomes 9/34 - 6/34, or (9-6)/34, or 3/34.
I guess I should also note that adding a negative number just means subtracting that number, so 9/34 + (-3/17) is the same as 9/34 - (3/17)