Question

WILL MARK BRAINLIEST!!!

Answer 1

9514 1404 393

Answer:

• a = 17
• ∠ABC = 78°

Step-by-step explanation:

The marked angles form a linear pair, so have a sum of 180°.

  (4a +10) +(6a) = 180

  10a = 170 . . . . . . . . . . subtract 10

  a = 17 . . . . . . . . . . . . . divide by 10

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Then the measure of angle ABC is ...

  ∠ABC = 4a +10 = 4(17) +10 = 68 +10 . . . . . substitute 17 for 'a'

  ∠ABC = 78°