Question 1890
i am not sure if i can do this...is there some other piece of info you have not given us?

Let s = number of students on Bee
Let c = cost for a student on Bee

so, on Bee, the cost of the boat is sc

Now, with 5 less students, the cost of the boat per person is c-50 whilst the total cost, sc/2 = (c-50)(s-5) --eqn1

Also, with 10 more students, the cost of the boat per person is c-30 whilst the total cost, 1.2sc = (c-30)(s+10) --eqn2

eqn1 becomes sc = 2(c-50)(s-5)
eqn2 becomes sc = (5/6)(c-30)(s+10)

we can equate these two and then expand the brackets and simplify to give

(7/6)cs - (110/6)c - 75s + 750 = 0

but i cannot figure out what to do next, but i could be missing something obvious - just not sure.

cheers
Jon.