R, S, T, U, V and W are six students. In how many ways can they be seated in a row if:
a. there are no restrictions on the seating.
b. R and S must sit beside each other.
c. U, V and W must sit beside each other.
d. R and W must sit at the end of each row.
a. there are no restrictions on the seating.
b. R and S must sit beside each other.
c. U, V and W must sit beside each other.
d. R and W must sit at the end of each row.