Question 328872
{{{16+8r-4r+4=24}}}
{{{(8r-4r)+(16+4)=24}}}<--- Gather like terms, then simplify
{{{4r+20=24}}}
{{{4r+20-20=24-20}}}<--- Subtract 20 from both sides.
{{{4r=4}}}
{{{(4r)/4=4/4}}}<--- Divide both sides by 4.
{{{(4/4)r=1}}}<--- Simplify
{{{r=1}}}