Question 159410
I assume you want to solve the equation for the given variable??
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1.{{{ad=f}}} Divide both sides by d.
{{{(ad)/d=f/d}}}
{{{(a*cross(d))/cross(d)=f/d}}}
{{{a=f/d}}}
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2.{{{n+3=q}}} Subtract 3 from both sides.
{{{n+3-3=q-3}}}
{{{n=q-3}}}
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3. Not sure about this one, should one of those "=" signs be a "+" sign? 
Please re-post this third part with a clarification.