Yvaries directly with x. if y is 45 when x is 15; what is y when x is 5

The size of a certain cell is 2.5*10^-9m. another cell is 1.5*10^3 times larger. how large is the larger cell in scientific notation?

Write an inequality for this sentence the quotient of a number and -5 increased by 4 is at most 8

Keith runs 5 miles in 38 minutes. at the same rate, how many miles would he run in 57 minutes