First you need to find what 2/3 equals
to do this, take 99 divided by 3
99/3=33
if 1/3 equals 33, two thirds would be 33x2
33x2=66
now, you need to find 1/2 of 66. this can be done 2 different ways
1. 66 divided by 2 - 66/2=33
OR
2. 66 x 1/2 = 33 OR 66 x .5 = 33
The answer is 33 kilograms