PLEASE I NEED HELP ASAP

Armando found the volume of the figure below by using the steps shown.
A rectangular prism with a length of 18 inches, width of 5 inches, and height of 8 inches. A triangular prism with a base of 18 inches and height of 6 inches. The prism has a height of 5 inches.

Total Volume = Volume of rectangular prism + volume of triangular prism = 5 (8) (18) + one-half (6) (18) (8) = 720 + 432 = 1,152 cubic inches.

What mistake, if any, did Armando make?
Armando determined the volume correctly.
Armando used the wrong formula for the total volume.
Armando used the wrong dimensions for the triangular prism.
Armando did not apply the order of operations correctly.

Little’s law firm has just one lawyer. customers arrive randomly at an average rate of 6 per 8 hour workday. service times have a mean of 50 minutes and a standard deviation of 20 minutes. how long does a customer spend at little’s law firm on average?

Browning labs is testing a new growth inhibitor for a certain type of bacteria. the bacteria naturally grows exponentially each hour at a rate of 6.2%. the researchers know that the inhibitor will make the growth rate of the bacteria less than or equal to its natural growth rate. the sample currently contains 100 bacteria.the container holding the sample can hold only 300 bacteria, after which the sample will no longer grow. however, the researchers are increasing the size of the container at a constant rate allowing the container to hold 100 more bacteria each hour. they would like to determine the possible number of bacteria in the container over time.create a system of inequalities to model the situation above, and use it to determine how many of the solutions are viable.

Asystem of equations has 1 solution.if 4x-y=5 is one of the equations , which could be the other equation ?