Jackson Wan's answer to The best one's Secondary 1 Maths Singapore question.

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Jackson Wan
Jackson Wan's answer
18 answers (Tutor Details)
1st
Eq opposite angles
Angle AOC = Angle DOB
3a +40 = a + 60

2a = 20

a = 10 deg*

angles on straight line
4b +10 + a + 60 = 180 deg
4b + a + 70 = 180
4b + a = 110
since a = 10,
4b = 100
b = 25 deg*