so the numbers are x and y
x:y=5:4
x/y=5/4
this means that x is worth 5 units and y is worth 4 units so
x:y=5:4, therefore it can be represented by
x:y=5z:4z
we know that they add to 720
720=5z+4z
add like terms
720=9z
divide by 9
80=z
multiply by 4
320
80=z
mutipply by 5
400
the numbers are 400 and 320