can i get help please i dont understand this

Answer:
Step-by-step explanation:
inside angle = 180 = 2x + 2x + 20 + 3x - 10 + 2x - 10
substitute the value of x = 20 into angle L, M, N, P
L = 2x + 20
L = 2(20) + 20
M = 3x - 10
M = 3(20) - 10
N = 2x - 10
N = 2(20) - 10
P = 2x
P = 2(20)
∠L + ∠M + ∠N + P = 180
60° + 50° + 30° + 40° = 180