I don't get how to do elimination

Mrs. simpons drove 105 miles in 2 1/2 hours. What was Mrs. Simpons speed in miles per hours?

Rina drew a scale drawing of the elementary school. The scale of the drawing was 1 centimeter : 3 meters. If the school yard is 17 centimeters in the drawing, ]'how wide is the actual school yard?

If 3 inches is equal to 7.62 centimeters, how many inches is 92 centimeters?

In order to determine an interval for the mean of a population with unknown standard deviation a sample of 61 items is selected. The mean of the sample is determined to be 23. The number of degrees of freedom for reading the t value is a. 22 b. 23 c.

A list of the perfect cubes that are between 100 and 600 ,

A certain type of bacteria, given a favorable growth medium, doubles in population every day. If you begin with 10 bacteria, how many days will it take for the population to reach 20,000

If you wanted to find the depth of a submarine during a dive, would it be more reasonable to use an equation with the rate in feet per minute or feet per hour? Explain your reasoning.

What value of satisfies the equation 2n-3 (4n+5) = -6 (n-3) - 1

A supplier has delivered 9 pallets of material to the hardware store. The delivery needs to be inventoried in 1.5 hours. How many pallets must be inventoried per hour?

Solve x for 3 х - 1 = - 13