Which major mathematical idea that the aztecs develop? a) a 365 day solar calendar b) the concept of zero c) numbering system based on 20 d) a counting system of three symbols.

Due to what conditions were slaves brought into brazil to work the fields? the climate was similar to that of africa. the indigenous workers were hired as managers. the indigenous workers had died from exposure to diseases from europe. slaves from africa were already used in other regions and brazil was the next location.