Someone please help this is my last question and I’m already fail so please give right answer if you can :)

Answer: x=20
Step-by-step explanation:
the following angles are supplementary so they will add up to equal 180
4x+21 +2x +39=180
step 1 combine like terms
6x+60=180
step 2 subtract 60 from each side
6x=120
step 3 divide each side by 6
x=20