How many different seating arrangements satisfy all the conditions?
Solution
G is in seat 4 and A is to its right. If A is in 5 or 6, B must be in the other of 5 and 6 (B cannot be in 4 or 7). Then C, D, E and F take seats 1, 2, 3 and 7: D two right of E forces E = 1 and D = 3, so C and F are in 2 and 7; C cannot be in 7, so F = 7, which is not to the left of C. So A = 7 and B = 6.
That leaves seats 1, 2, 3 and 5 for C, D, E and F, with D two seats right of E (E in 1 and D in 3, or E in 3 and D in 5) and F not in 3 or 5 (next to G).
E = 1, D = 3: F = 2 and C = 5 (C not at an end, right of F). E = 3, D = 5: F = 1 and C = 2. So exactly 2 arrangements: E F D G C B A and F C E G D B A.
