If the average teenager's body contains 4.5 litera of blood, how many literas of blood would there be in a class of 30 students?

135 liters,

Explanation:

just multiply 4.5 x 30

4.5×30=135

135 literas of blood in a classs of 30 students.

Explanation:

answer; i believe the correct answer is (anemia);

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.