Answer :
4 / 30 = x / 75...4 drivers to 30 sq miles = x drivers to 75 sq miles
cross multiply
(30)(x) = (75)(4)
30x = 300
x = 300/30
x = 10 <== 10 drivers for 75 sq miles
cross multiply
(30)(x) = (75)(4)
30x = 300
x = 300/30
x = 10 <== 10 drivers for 75 sq miles