Question 831280
{{{(1+r)/(9+r)=3/4}}}
Cross multiply.
{{{4(1+r)=3(9+r)}}}
{{{4*1 + 4*r = 3*9+3*r}}}
{{{4r+4=3r+27}}}
{{{4r=3r+23}}}
{{{r=23}}}
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