all students = 150
M = 60
S = 45
M and S = 25
(a) At least one of the two requirements:
M or S = M + S - (M and S) = 60 + 45 - 25 = 80
(b) Exactly one of the two requirements:
(M or S) - (M and S) = 80 - 25 = 55
(c) Neither requirement:
(all students) - (M or S) = 150 - 80 = 70
That would be 1/5 in simplest form you can divide both numbers by 12 and when you do you get 1/5. Hope this helps!
Here, it helps to find a general expression for the nth term in the
sequence. Since the sequence is arithmetic, the general term is a_n = a +
bn, where b is the common difference. By inspection of the first few
terms we see the common difference is -4. Then by solving a_1 = a - 4x1 =
5, we obtain a = 9, so the nth term is: a_n = 9-4n. We then solve
a_n=-111 for n, so 9-4n=-111. Rearranging, we get 4n=9+111, or 4n=120,
or n=30. Thus there are 30 terms in the sequence.
t(1) = 1 = 2(1)-9 / 1 - a
1 - a = 2 - 9 = -7
a = 1 + 7
a = 8 answer