Answer: 26
Step-by-step explanation: Each number adds +1 as it goes to the next number. 6 to 8 shows a 2 increase. Then the next number gains a +1 increase. So 8 to 11 is 3, then another +1 increase. So 11 to 15
Another +1. 15 to 20 (5 increase). and lastly a 6 increase, 20 to 26