Simply take a ruler with centimeters on it and measure your desk.Tell the teacher you counted how many centimeters.
3427 + 65.75s = 5000 + 35.5s
65.75s - 35.5s = 5000 - 3427
30.25s = 1573
s = 1573 / 30.25
s = 52 seconds <== they are the same at 52 seconds
3427 + 65.75(52) = 6846
5000 + 35.5(52) = 6846
and their altitude is 6846 <===
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