Question

The answer is 144 but how?

Answer 1

x = 144°

the following ratio is true for the given circle

`(arc)/(circumference)` =
`(x)/(360)`

that is
`(2)/(5)` =
`(x)/(360)` ( since AB is 2/5 circumference )

cross-multiply

5x = 720 ( divide both sides by 5 )

x = 144

Answer 2

the angles around the point a total 360°
the lines AB and AC make a sector of the circle.
we are told that the circumference of that sector is 2/5 of the total circumference
so 360/5 ×2 =144