Solve as many as you can please

Gretchen is setting up for a banquet. she has 300 chairs and needs to distribute them evenly among t tables. how many chairs should she put at each table? write your answer as an expression.

If c(x) = 4x – 2 and d(x) = x2 + 5x, what is (cxd)(x)

Which shows the correct solution of the equation 1/2a+2/3b=50, when b=30?