Convert 1/2 into fourths. just multiply the denominator by 2 (2x2 = 4) and the numerator by 2 (whatever you do to the top, you do to the bottom).
1/2 is now 2/4. Now you have to add 6 and 1/4 to 2/4. (1/4 + 2/4) + 6 = 3/4 + 6 = 6 and 3/4.
So, 6 and 1/4 + 1/2 = 6 and 3/4