A vertical line on the value x = -4
use PEMDAS (parenthesis first)
4 * (x * 3) =
4 * 3x =
12x
The interval of hours represents the lifespan of the middle 68% of light bulbs, using the empirical rule is, 1210 hours to 1390 hours.
<h3>What is empirical rule?</h3>
According to the empirical rule, also known as 68-95-99.7 rule, the percentage of values that lie within an interval with 68%, 95% and 99.7% of the values lies within one, two or three standard deviations of the mean of the distribution.

Here, we had where mean of distribution of X is \mu and standard deviation from mean of distribution of X is \sigma
The amount of time a certain brand of light bulb lasts is normally distributed with a mean of 1400 hours and a standard deviation of 50 hours. Thus,

Using the empirical rule, the interval of hours represents the lifespan of the middle 68% of light bulbs is,

Thus, the interval of hours represents the lifespan of the middle 68% of light bulbs, using the empirical rule is, 1210 hours to 1390 hours.
Learn more about empirical rule here:
brainly.com/question/13676793
#SPJ1
-10= 4x
divide both sides by 4 to get x by itself
-10/4=4x/4
x= -10/4
reduce the fraction by dividing by 2
-10/2= -5
4/2= 2
Answer:
x= -5/2, x= - 2 1/2 , x=-2.5