A = (vf - vi) / t <== call this the "given equation"
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For t :
Multiply each side of the given equation by 't' : A t = (vf - vi)
Divide each side by 'A' : t = (vf - vi) / A
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For vi :
Multiply each side of the given equation by 't' : A t = (vf - vi)
Subtract ' vf ' from each side: A t - vf = -vi
Multiply each side by -1 : vf - A t = vi
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For vf :
Multiply each side of the given equation by 't' : A t = (vf - vi)
Add ' vi ' to each side: A t + vi = vf
