This is probably easy

5 hours

Step-by-step explanation:

Let's express each scenario as a function in a slope-intercept form, y = mx + b,

Where,

y = total amount of water

x = number of hours

m = rate of at which water is drained or filled per hour

b = initial quantity of water in the tank

✔️Equation for Tank A:

m = 2 gallons/hour = 2

b = 100 gallons = 100

Substitute m = 2 and b = 100 into y = mx + b:

y = 2x + 100

✔️Equation for Tank B:

m = 6 gallons/hour = -6 (this is negative 6 because water drains)

b = 140 gallons = 140

Substitute the values into y = mx + b

y = -6x + 140

✔️Set the two equation equal together to determine the number of hours (x) that must pass for the total amount of water (y) in tank A and tank B to be the same.

2x + 100 = -6x + 140

Collect like terms

2x + 6x = -100 + 140

8x = 40

Divide both sides by 8

x = 40/8

x = 5

Therefore, 5 hours must pass for the total amount of water in both tanks to be the same.

introduction, methodology, results, discussion

step-by-step explanation:

an observational study is one which consists of actual observation to record data and then analyse the data.

there are a number of factors that should be analyzed before starting an observational study.

the main four factors are:

i) introduction:   this should be analysed to check whether the purpose of the study is correctly established and the data recorded are appropriate for the study

methodology:   the method of collecting the data, such as whether randomly selected, and whether sample size matches with the population to be studied, whether questions asked are easy to answer by common men, etc.

results: then results such as summary of data with comments should be studied thoroughly

discussion:   the last is the discussion, this can be either by management people or persons who are all interested , etc.