Answer:
The number of people in the junior class = 180 people
Step-by-step explanation:
let number of people in junior class be x
By 7:00PM, 1/3 of the junior class had arrived at a school dance. This means x/3 juniors arrived by 7:00 PM
By 8:00PM, 30 more juniors had arrived, raising the attendance to 1/2 of the junior class. This means that 30 juniors plus 1/3 of the total number of juniors equal 1/2 of the total number of juniors
30 + x/3 = x/2
(90+x)/3 = x/2
Cross multiplying
2(90+x) = 3x
180 +2x = 3x
180 = 3x-2x
180= x
x = 180
