A social networking site recorded that 80% of the people who became members of the site one month were between 30 and 40 years old. The equation below represents this information, where x represents the total number of people who became members of the site that month.

x = 0.8x + 72

How many people who became members of the site that month were between 30 and 40 years of age?

Question

A social networking site recorded that 80% of the people who became members of the site one month were between 30 and 40 years old. The equation below represents this information, where x represents the total number of people who became members of the site that month.

x = 0.8x + 72

How many people who became members of the site that month were between 30 and 40 years of age?

phi · Answer

x is the total number of people who joined.  You need to find 0.8*x  (80% of x)
The first step is to find x using their equation.  To do this, subtract 0.8x from both sides
x-0.8x = 0.8x - 0.8x +72
Can you finish, and find the value of x?