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Answer:
Option (3).
Step-by-step explanation:
Option (1).
3(x - 1) = x + 2(x + 1) + 1
3x - 3 = x + 2x + 2 + 1
3x - 3 = 3x + 3 [Not True]
Therefore, this equation is not an identity.
Option (2).
x - 4(x + 1) = -3(x + 1) + 1
x - 4x - 4 = -3x - 3 + 1
-3x - 4 = -3x - 2 [Not true]
Therefore, this equation is not an identity.
Option (3).
2x + 3 =
2x + 3 = 2x + 1 + 2
2x + 3 = 2x + 3 [True]
Therefore, this equation is an identity.
Option (4).
3x - 1.5 = 3x + 3 - x - 2
3x - 1.5 = 2x + 1 [Not true]
Therefore, this equation is not an identity.
28 men are needed to paint the room in 3 hours
<h3><u>Solution:</u></h3>Given that it takes 12 hours for 7 men to paint a room
We are asked to find number of men required to paint the room in 3 hours
Recognize, "paint the room" is 1 task. One job.
7 men -------- 12 hours ------ 1 job
(7/7) = 1 men ------- 12 x 7 (84) ------- same 1 job
The one men is rate is 84 hours to do the job
We can express this as 1/84 jobs per hour, the one-person rate
Now lets find how many men needed to paint the room in 3 hours
Let the required number of men for 3 hours be "a"
The rates of each person is simply additive.
corresponds to rate x hours = jobs and "a" is a variable for how many men
Thus 28 men are needed to paint the room in 3 hours