Trying to find the equivalent ratio with lower terms

A. 30:36=20: ?
B. 21:35=? :20

An an average person has 6×10 by the power of two as many red blood cells as white blood cells a small sample of the blood has 7×10 by the power of three white blood cells about how many red blood cells are in the sample

Satchi found a used bookstore that sells pre-owned dvds and cds. dvds cost $9 each, and cds cost $7 each. satchi can spend no more than $45.

Factor the expression using the gcf. the expression 21m−49n factored using the gcf