We need to first find the constant of proportionality
Let k be the constant of proportionality
If x varies inversely with y, then;
x ∝ 1/y
x = k/y
when x = 10 and y=3, substitute the values in the above and solve for k
10 = k/3
cross -multiply
k = 30
To find y when x = 6, simply substitute the value of k=30 and x=6 in the first equation and solve for y
That is;
6 = 30/y
cross-multiply
6y = 30
Divide both-side by 6
y = 5