What's 2 / 5 times 4 plus 2 / 5? What's 20.5 minus 4 and 3 / 7 minus 5 and 4 / 7

What's 2 / 5 times 4 plus 2 / 5? What's 20.5 minus 4 and 3 / 7 minus 5 and 4 / 7

2 / 5 times 4 plus 2 / 5 equals 2
20.5 minus four and seven thirds minus five and seven quarters equals 10.5

Carefully observe the arrangement of the sequence and fill in the corresponding numbers 6, 8, 10, 11, 14, 14, (?) in the box
Please don't just give the result, please give the reason,

6、8、10、11、14、14、（18）
Odd term 6 + 4 = 10 10 + 4 = 14 14 + 4 = (18)
Even term 8 + 3 = 11 + 3 = 14

24.6 minus 14.9 plus 5.1 can be calculated simply

∵ 24.6 minus 14.9 plus 5.1, namely: 24.6-14.9 + 5.1,
∴24.6-14.9+5.1
=24.6-14.6-0.3+5.1
=10+4.8
=14.8