what number should be added to -5/7 to get-7/9

what number should be added to -5/7 to get -7/9

let the required number is x.

According to the question,

-5/7+x=-7/9

Or, x=-7/9 + 5/7

Or, x=(-49+45)/63

Or, x=-4/63

Required number=-4/63