I need to find the missing angles

If a and b are the measures of two first quadrant angles and sin a = 4/9 and sin b = 2/5 find sin(a+b).

Find the indicated value, where g(t) = t^2-t and f(x)= 1+x a. -2 b. 0 c. 2 d. 8

For a field trip to the zoo, 4 students rode in cars and the rest filled nine busess. how many students were in each bus if 472 students were on the trip