USAAAO — 2019 First Round

The Sun’s differential rotation can be estimated with the equation ω = X + Y sin²(φ) + Z sin⁴(φ), where ω is angular velocity in degrees per day, φ is solar latitude, and X, Y, and Z are constants equal to 15, -2.5, and -2 degrees per day. Two sunspots are spotted along the same solar meridian, one at 0° and the other at 40°. Assuming they do not disappear or change latitude and move with the solar surface, after how many days will the sunspots be aligned once again? Round to the nearest day.