Question 458223
{{{7/4a^3b^2 - 5/3a^2b^3}}}....common denominator is {{{12a^3b^3}}}


{{{7*3b/12a^3b^3 - 5*4a/12a^3b^3}}}


{{{(21b- 20a)/12a^3b^3}}}.....condition: {{{a}}} and {{{b}}} cannot be zero