How natural selection could lead to a change in allele frequency, think about which color may go away and which color will become more common

it means

miss jennifer is buying pencils in packs of 12, notebooks in packs of 16, and red pens in boxes of 20. she needs to have the same number of pencils, notebooks, and red pens. how many packs of each type should she buy?

answer mine : )

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.