Answer:
x = 25°
Explanation:
Here given a straight line whose angle equals to 180°
2x + 10 + 4x + 20 = 180
group terms like this ↓
2x + 4x + 10 + 20 = 180
simplify all variables ↓
6x + 30 = 180
changing sides changes addition to subtraction ↓
6x = 180 - 30
6x = 150
changing sides changes multiplication to division ↓
x = 150/6
final answer ↓
x = 25°