Question

Ignore the erase marks but i have no clue how to do this. please help asap

Answer 1

Since they're vertical angles, they're equal in degree measure

since they're equal, we can make the two expressions equal to each other

5a - 1 = 2a + 20
add 1 to both sides

5a = 2a + 21
subtract 2a from both sides

3a = 21
divide both sides by 3a

a = 7

now, plug the answer you found for a into one of the two expressions

5a - 1 becomes (5*7) - 1, which equals 34

to double check that they're equivalent (since they're vertical angles)

2a + 20 becomes (2*7) + 20, which equals 34

both angles are 34 degrees!