Question

What no. Should be added to -5by8 to get 5by9

Answer 1

5/9=-5/8+x
5/9+5/8=x
85/72=x
hope this helps you quickly

Answer 2

let the number that should be added be x
then
$\frac{ - 5}{8} + x = \frac{5}{9} \\ x = \frac{5}{9} + \frac{5}{8} \\ x = \frac{40 + 45}{72} \\ x = \frac{85}{72}$
so the no. that should be added is 85/72