75% of an unknown number of people is 480 people.
We translate this sentence into an equation and we solve the equation.
Let x = number of people who were surveyed.
75% of x = 480
75% * x = 480
0.75x = 480
x is being multiplied by 0.75. We want x alone, so we divide 0.75x by 0.75 to get x alone. Since we must do the same to both sides of an equation, we divide both sides of the equation by 0.75.


Answer: 640 people were surveyed.