Question 316429
Please try MY website.  More on that later.  First, let me solve your problem.  


{{{Q=(I^2Rt)/J}}} for J.


First, clear the fraction by multiplying both sides by J:
{{{J*Q = J*((I^2Rt)/J) }}}
{{{JQ=I^2Rt}}}


Now, since you are solving for J, you need to get the J all by itself.  What you have is JQ, which means J*Q, where the operation is MULTIPLICATION.  You need to get the J by itself, which means that you need to UNDO the Q variable.  You UNDO multiplication by DIVIDING, so DIVIDE both sides by Q to leave the J alone:
{{{(JQ)/Q=(I^2Rt)/Q}}}
{{{J=(I^2Rt)/Q}}}


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In addition to all of this written explanation, I have FREE VIDEOS of me teaching in some of my classes a few years ago before I retired.  To see the videos, from my Homepage, look for the link "Rapalje Videos in Living Color."  There is a video on "Fractional and Literal Equations" in Intermediate Algebra.  The Literal Equations are at the end of this video, but you can fast-forward to the Literal Equations part of the video.


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Dr. Robert J. Rapalje, Retired
Seminole State College of Florida
Altamonte Springs Campus