Answer:
[tex]s=20[/tex]
Step-by-step explanation:
By the Exterior Angle Theorem, we know that the exterior angle is equal to the sum of the two, opposite interior angles.
In other words:
[tex]4s=(3s-20)+(2s)[/tex]
Solve for s. Combine like terms:
[tex]4s=5s-20[/tex]
Subtract 5s from both sides:
[tex]-s=-20[/tex]
And divide both sides by negative one. Therefore:
[tex]s=20[/tex]
