Find the mass and center of mass of the solid e with the given density function ρ. e is the tetrahedron bounded by the planes x = 0, y = 0, z = 0, x + y + z = 4; ρ(x, y, z) = 8y.

Math it's appreciated. (picture provided)

Due to financial difficulties the owner of 4 skateboard stores is going to close 2 of his stores. based on the money earned at each store, which two stores should remain open?

Atruck can be rented from company a $50 a day plus $0.60 per mile. company b charges $20 a day plus $0.80 per mile to rent the same truck. find the number of miles in a day at which the rental costs for company a and company b are the same