Question 903861
First get the denominators to be same. Once you do, you can add.


{{{1/4 + 3/9}}}


{{{(1/4)*(9/9) + 3/9}}}


{{{9/36 + 3/9}}}


{{{9/36 + (3/9)*(4/4)}}}


{{{9/36 + 12/36}}}


{{{(9 + 12)/36}}}


{{{21/36}}}


{{{7/12}}} Don't forget to reduce fully


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So, {{{1/4 + 3/9 = 7/12}}}