The sum of the interior angles of a polygon is 1980°.how many sides has the polygon

To know how many sides has this polygon, knowing the sum of their interior angles, we can use this expression:

b = (n-2) * 180

Where b is the sum of the interior numbers and n the number of sides.

Knowing this, we can replace, as we kno w it

b = (n-2)) * 180

1980 = (n-2)*180

We can know solve the equation

We can use this distributive property to operate the parenthesis, which says that if we find this expression a(b+c), we can operate doing ab+ac, and, if we substract, we can also use it, as a(b-c) = ab-ac

1980 = (n-2)*180

1980 = 180n - 180*2 = 180n - 360

1980 = 180n - 360

1980 + 360 = 180n

13 = n

So we know the polygon will have 13 sides..

let y equal to

the total fare and x is the mile of taxi ride. so the equation is

y = 0.55x + 1.75

since susie has

$10 to spend for a taxi cab, so he can have

10 = 0.55x +

1.75

x = 15 miles of

taxi ride

so the system of

inequality is

10 < 0.55x +

1.75

x > 2