Can someone help me with this question. Need answer and explanation/work. Thank you.

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).

Our goal is to collect email addresses from 60% of customers who purchase a product." so that means if i talk to 95 customers, i need to persuade to provide an email address?

Solve the equation using the given values: x= -2.5; y= -7.51. 2xy + 2x²