Here two charges are given +1 microcoulomb and +5 microcoulomb. To find the force of attraction or repulsion between them we use coulomb's law. Which states that the force between the two charges is directly proportional to the product of two charges and inversely proportional to the square of distance between them i.e.
Now first we find the force on +1 microcoulomb charge due to +5 microcoulomb charge i.e. Using coulomb's law, we get
is the distance between these two charges…..(1)

Similarly, we can write the force on +5 microcoulomb charge due to +1 microcoulomb charge i.e.

By using Coulomb's law, we get
, here also r is the distance between these charges….(2)

Now, in order to find the ratio between both the forces we can divide the equation (1) by equation (2), we get

Hence, the ratio between the forces is .