Answer:
I and III
Step-by-step explanation:
The three scores are 86, 74, and an unknown score x. The average (i.e. the sum divided by how many there are) is 80, so we have

Multiply both sides by 3 and you get

Subtract 160 from both sides to get

Note: you could solve this exercise very quickly if you notice that the two numbers, 86 and 74, are symmetrical with respect to 80, which is the average. So, the third number must be the average.
First one subtract 4/5 and 3 3/4 then divide both sides by the number you get from subtracting.
Answer:
y = (-1/7)x + (24/7)
Step-by-step explanation:
The general structure of a line in slope-intercept form is:
y = mx + b
In this form, "m" represents the slope and "b" represents the y-intercept.
You have been given the value of the slope (m = -1/7). You have also been given values for "x" and "y" from the point (3,3). Therefore, you can substitute these values in for their variables and simplify to find the value of the y-intercept.
y = mx + b <----- Slope-intercept form
y = (-1/7)x + b <----- Plug -1/7 into "m"
3 = (-1/7)(3) + b <----- Plug in "x" and "y" values from point (3,3)
3 = -3/7 + b <----- Multiply -1/7 and 3
24/7 = b <----- Add 3/7 to both sides
Now that you know that m = -1/7 and b = 24/7, you can determine the formula satisfying the given information.
y = (-1/7)x + (24/7)