Price for a radio = $ 40 for supply 90 radios in a month.
Ratio of increase in price to the number of radios supplies in a month 4:8 that is 1:2.
New unit price given = $76.
Difference in unit price given in starting and New unit price = 76-40=$36
So, increase in unit price = $36.
Let us assume number of supplied increased = x radios for increase in unit price $36.
So, we can setup a perportion as,
1/2 = 36/x.
On cross multiplication, we get
1*x = 2*36
x= 72.
So, 72 is the increased number of radios in 90 radios.
That is 72+90 = 162 radios each month.
Therefore, 162 radios are supplied if their per unit price is $76.