Two submersibles, one red and one blue, started rising toward the surface at the same time. They each rose at a constant speed. The red submersible started rising from an altitude of 80 meters below the surface. After 30 seconds, it :wa s6 meters below the surface. The following equation gives the altitude (in meters relative to the surface) of the blue submersible as a functior of time (in seconds).

A=-90+0.6t

Which submersible started rising from a higher altitude?