To find the price of the flowers in September, divide the current price by 1 + the percent of increase:
September price = $1.50/1.20 = $1.25
The price of the flowers in September was $1.25 ( Check 1.25 x 1.20 = 1.50)
Total money raised in September = $1.25 x 900 = $1,125
40% earned = 0.4 x $1,125 = $450
Total money raised in October = $1.50 x 700 = $1,050
40% earned = 0.4 x $1,050 = $420
$450 – $420 = $30 more in September.
The class earned more money in September by $30 more.