Find sin ( a +b) if sin a + -20/29 where a is in the fourth quadrant and tan (b) = -15/8 where b is in the second quadrant

Np4=12np2 with clear explanation.

With this one. will mark brainliest

Elena and her husband marc both drive to work. elena's car has a current mileage (total distance driven) of 15,000 and she drives 23,000 miles more each year. marc's car has a current mileage of 46,000 and he drives 9,000 miles more each year. will the mileages for the two cars ever be equal? explain.