Question

AOB and COD are straight lines. Find the value of unknowns.​

Answer 1

Answer:

$6b + 3b = 180 \\ 9b = 180 \\ b = 180 \div 9 = 20 \\ 3b = 60 \\ a + 3b = 180 \\ a = 180 - 60 \\ a = 120$