Answer:
0.7
Step-by-step explanation:
8.40 divided by 12
= 0.7
Step-by-step explanation:

Combine like terms on left hand side. Like terms are those which have the same base. Only coefficients of like terms can be added or subtracted.
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Transpose 2x to left hand side and change it's sign.
Similarly , Transpose 10 to right hand side and change it's sign.
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Divide both sides by 6
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Given that she slides at a rate of 8m/s and that she was 5 m of the ground after 3 seconds, the number of seconds it takes her to reach the ground from the current position is given by:
Therefore, the number of seconds it takes her to slide to the ground from the top is given by: