Since we don't know either b or y, we have to give the answer in terms of b and y. The sum of 9 and b is (9+b), so 2/3 of the sum is 2(9+b)/3. The product of 7 and y is usually written 7y (the multiplication sign is understood to be between 7 and y). So the sum of the two is 2(9+b)/3+7y. This can also be written 2/3*9+2b/3+7y, which equals 6+2b/3+7y.