- A72
- B160
- C80
- D88
Step-by-Step Solution
Let angle = , supplement → → → °.
Answer: C) 80
Find the value of the angle that is 20° less than its supplement (in degrees).
Class 7Lines and AnglesLines and Angles
Key idea: Solving 'find the angle' problems
Most Class-7 angle problems give you one or two angle measures and ask you to find an unknown one. The recipe:
1. Identify the relationship: vertically opposite? linear pair? corresponding? alternate?
2. Write an equation: equal-to or sum-to-180.
3. Solve for the unknown.
4. Mark it back on the diagram and sanity-check (acute should look acute, obtuse should look obtuse).
1. Identify the relationship: vertically opposite? linear pair? corresponding? alternate?
2. Write an equation: equal-to or sum-to-180.
3. Solve for the unknown.
4. Mark it back on the diagram and sanity-check (acute should look acute, obtuse should look obtuse).
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