Final answer:
In 20 school days, Bryson will have both math and science homework on the same night for a total of 3 times.
Step-by-step explanation:
To find the number of days Bryson will have both math and science homework on the same night in 20 school days, we need to find the least common multiple (LCM) of 2 and 3. The LCM of 2 and 3 is 6. So, Bryson will have both math and science homework on the same night every 6 days. If we divide 20 by 6, we get 3 remainder 2. This means that in 20 school days, Bryson will have both math and science homework on the same night for a total of 3 times, with 2 additional days left without both subjects.