Question 163177
When adding and subtracting fractions you need to have the same denominators.
Make the denominators 17*18.
{{{3/18 + 6/17=(3/18)(17/17)+(6/17)(18/18)}}}
{{{3/18 + 6/17=(3*17)/(17*18)+(6*18)/(17*18)}}}
{{{3/18 + 6/17=51/(17*18)+108/(17*18)}}}
{{{3/18 + 6/17=159/(17*18)}}}
{{{3/18 + 6/17=(53*cross(3))/(17*6*cross(3))}}}
{{{3/18 + 6/17=(53)/(102)}}}
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Make the denominators 40.
{{{-16/40+(-13/20)=-16/40+(-13/20)(2/2)}}}
{{{-16/40+(-13/20)=-16/40+(-26/40)}}}
{{{-16/40+(-13/20)=-42/40}}}
{{{-16/40+(-13/20)=-21/20}}}