<span>When creating a subset of 5 elements from 7 elements, order should not matter. Therefore, we use the combination formula over the permutation formula.
The combination formula given n elements total and r elements used is n! / [r!*(n-r)!]. Substituting 7 for n and 5 for r, we get:
7! / (5!*2!) = 7*6 / 2 = 21
21 subsets can be created</span>
Answer: 927
Step-by-step explanation:
9) 6/10
10)14/21
11) 4/5
12)12/40
13)7/12
14)45/80
15) 27/108
16)7/56
17) 6/27
18) 70/112
Rewrite equation so that it is homogeneous .

Solve characteristic equation:
The solutions to the homogeneous equation are:

Finally you need the constant term in "cy" to equal 'd' to satisfy the particular solution.
360 - 20 + 2x = 360
340 + 2x = 360
2x = 20
x = 10