Mark and clean his father's office in 30 minutes his younger sister lynn can clean the office in 40 minutes how long will it take the two of them together to clean the office

Ametalworker has a metal alloy that is 30? % copper and another alloy that is 55? % copper. how many kilograms of each alloy should the metalworker combine to create 90 kg of a 50? % copper? alloy?

Roger could feed 5 walruses with 4 kilograms of fish. how many walruses could he feed with 7.2 kilograms of fish?

50 plz, given the system of equations, match the following items. x + 3 y = 5 x - 3 y = -1 a) x-determinant b) y-determinant c) system determinant match the following to the pictures below.