If 315 days have passed, how many grams of iodine-125 will remain undecayed?
(my teacher has the answer online and he got approximately 15 just want to know how he got there)

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.

the second type of galaxy is called a barred spiral, which has a thing called a bar straddling the nucleus

i believe the answer is snake.