If ∠A and ∠B are supplementary angles and m∠B = (x + 20)°, then

1.	If ∠A and ∠B are supplementary angles and m∠B = (x + 20)°, then what would be m∠A?
Answer» Since, ∠A and ∠B are supplementary angles. ∴ m∠A + m∠B = 180 ∴ m∠A + x + 20 = 180 ∴ m∠A + x + 20 – 20 = 180 – 20 ….(Subtracting 20 from both sides) ∴ m∠A + x = 160 ∴ m∠A + x – x = 160 – x ….(Subtracting x from both sides) ∴ m∠A = (160 – x)° ∴ The measure of ∠A is (160 – x)°.

If ∠A and ∠B are supplementary angles and m∠B = (x + 20)°, then what would be m∠A?

Answer»

Since, ∠A and ∠B are supplementary angles.

∴ m∠A + m∠B = 180

∴ m∠A + x + 20 = 180

∴ m∠A + x + 20 – 20 = 180 – 20 ….(Subtracting 20 from both sides)

∴ m∠A + x = 160

∴ m∠A + x – x = 160 – x ….(Subtracting x from both sides)

∴ m∠A = (160 – x)°

∴ The measure of ∠A is (160 – x)°.