Answer:
865
Step-by-step explanation: The set of possibilities are:
Subcommittee is of 4 people according to:
4 teachers 0 other member total possibilities 1
3 teachers 1 teachers C₄,₃ = 4 and other member 6 6*4 = 24
2 teachers 2 C₄,₂ = 4!/2! = 12 2 (om) and C₆,₂ = 6!/4! = 30
30*12 = 360
1 teacher 3 (om) 4 and C₆,₃ = 6!/3! = 120
120*4 = 480
Total ways of committee 1 + 24 + 360 + 480 = 865
-1 - (-7) = 6
5 - (-1) = 6
11 - 5 = 6
The common difference is 6.
If you add 6 to a term, you get the next term.

10000+4.8%=10480
10480+4.8%=10983.04
10983.04+4.8%=11510.22592
so 3 years
Any of the tens i think (10=60, 20+50, etc.), but i am not too sure what is implied by regrouping. if i am right in thinking this only means "carrying" a digit after adding, then anything that adds up to 70 would work unless the sum of the digits in the ones place exceeded 9.