In the expression 6:15 = X:45, the unknown X is equal to

Prior to the late twentieth century, what was the most common form of heart disease?

A) Rheumatic heart disease B) Coronary thrombus C) Arteriosclerosis D) Coronary artery disease

Which type of lock is found in private residences, commercial buildings, and industrial buildings?

A. Circular B. Mortise C. Cylindrical D. Multiple bolts