First, convert your mixed numbers into improper fractions, so 8+3/8=69/8 and 2+1/3=7/3. Now you have 69/8=r-(7/3). Now, add 7/3 to both sides, so (69/8)+(7/3)=r. Now, just add your fractions, so (69/8)+(7/3)=207/24+56/24=(207+56)/24=263/24. If you need to, this can be converted back into the mixed number 10+23/24.
