The discriminant is

which is 0.
Since the discriminant is 0, there is only one real solution.
An equation that would represent the relationship between cost and revenue would be: 7.50t + 15s = 525
Hope this helps!! :)
YZ is the diameter, so arc YZ = 360°/2 = 180°
arc XZ = 360° - arc YZ - arc YWX = 360° - 180° - 100° = 80°
∠XYZ is an inscribed angle <span>so it is equal to half the arc XZ
</span>∠XYZ = 80°/2 = 40°