Answer:
-1
Step-by-step explanation:
4u-5v=23
-2(2u+4v=16) We multiply by -2 here to destroy u's.
4u-5v=23
-4u-8v=16 we addition both processes
-13v=39 so, v=-3
4u-5(-3)=23, 4u=8 so, u=2
u+v= -3+2= -1
It will take 0.556 seconds for an echo to reach one's ears
<h3>Calculating the time to hear an echo</h3>
From the question, we are to determine how long it would take an echo to reach one's ears
From the formula,

NOTE: To hear an echo, the sound will travel to and fro, hence, it will cover twice the distance
From the given information,
Distance = 92.0 m
NOTE: Speed of sound in air at 0 °C ≅ 331 m/s
Putting the parameters into the formula, we get


Time = 0.556 secs
Hence, it will take 0.556 seconds for an echo to reach one's ears.
Learn more on Calculating the time to hear an echo here: brainly.com/question/16676723
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Answer: 59,399,752,026
Step-by-step explanation: 2,493,483 · 23,822 = 59,399,752,026
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Answer:
First one is c because 3 1/2 - 1/2=3
Second one is also c because 0.9x2=1.8
And third one c is because 2 2/3:3/1=1 1/8