A. write an expression for the total cost of three types of tickets .
b. the andrews family bought 2 adult tickets,3 children's tickets, and 1 senior ticket evaluate your expression in part a to find the total cost of the tickets.
c. the spencer family bought 4 adult tickets and 2 childrens tickets. did they spend the same as the andrews family explain

If youre writing an exprssion all you need to do is make variables and multiply by the given number A, C, and S will be our variables.
2A + 3C + 1S = Total cost for andrews family 

4A + 2C = Total cost for Spencers family

Now, Does 2A + 3C + 1S = 4A + 2C

lets say A = 5 , C = 3 , and S = 2
2(5) + 3(3) + 1(2) = 4(5) + 2(3) 
10 + 9 + 2 = 20 + 6
21 = 26 

if this is your example then No, the spencers family spent more than the andrews family, youll have to do the math differently and may come up with a different answer if you were given values that you didn't give us, but this is how its done :) 

Hope this helps!