Homework, please help, bot answers/ point grabbing = reported

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).

Is δ pmr similar to δ smn ? if so, which postulate or theorem proves these two triangles are similar?

What are the solutions of the equation? 16x^2 + 24x + 5 = 5 a. 1/4, 5/4 b. -1/4, -5/4 c. -1/4, 5/4 d. 1/4 , -5/4