Right now Seth’s age is 4/5 the age of his brother Eric. Twenty-one years ago, Eric was twice as old as Seth. What are their ages now?

We are told that 21 years ago, Eric was twice as old as Seth. So, Eric was 2{(4/5)x-21} years old 21 years ago (just multiply Seth's age 21 years ago by 2).

Step-by-step explanation:

(sin 42)/31. = sinx)/37

sinx = 37 (sin42)/31

= 37× 0.66/31 = 0.787

x= 51.9

other angle opposite to y = 180-51.9-42

= 180- 93.9 =86.1

so

sin42)/31 = sin 86.1)/y

0.021 = 0.997 /y

y= 0.997/0.021 =47.47