Answer the question from the attachment.

So if you want to find x then all you have to do is follow this 
(20x + 10)/2 = 16x - 1
10x + 5 = 16x - 1 
6x = 6
x = 1   

Angle at centre = 2 * Angle at circumference.

Angle at centre = 20x + 10

Angle at circumference = 17x - 2

20x + 10 = 2*(17x - 2)
20x + 10 = 2*17x - 2*2
20x + 10 = 34x - 4
20x - 34x = -4 - 10
-14x = -14

x = -14/-14
x = 1.

1st Option.
 

80 minutes ; $25

Step-by-step explanation:

Let x = number of minutes

Plan A :

17 + 0.1x - - - (1)

PLAN B :

13 + 0.15x - - - (2)

Both plans will cost the same when ;

17 + 0.1x = 13 + 0.15x

Solve for X

0.1x - 0.15x = 13 - 17

-0.05x = - 4

divide both sides by - 0.05

-0.05x / - 0.05 = - 4 / - 0.05

x = 80 minutes

Amount :

17 + 0.1(80) = 17 + 8 = $25