Answer:
Problem 4: x = -11
Problem 5: x = -7
Step-by-step explanation:
Problem 4:
x + 51 + 60 + 80 = 180
x + 51 + 60 + 80 - 51 - 60 - 80 = 180 - 51 - 60 - 80
x = -11
Answer: x = -11
Problem 5:
45 + 52 + x + 90 - 90 - 52 - 45 = 180 - 90 - 52 - 45
x = -7
Answer: x = -7
