1. Sally bought identical red files. Each red file costs $1.40. When Sally bought 1 more blue file at $4.60, it increased the average cost of the red files to $1.80. How many files did Sally buy in total?

2. There are a total of 200 blue, green and red balls. There are as many red balls as blue balls. There are twice as many red balls as blue balls. There are fewer green balls than red balls. The number of blue balls and red balls in each group is less than 100 and divisible by 3 and 4. How many green balls are there?

3. Bella, Cody and Deborah had a collection of stickers. Cody and Deborah collected 7/10 of the stickers. Bella and Deborah collected 6/7 of the stickers. Bella and Cody collected 620 stickers. How many more stamps did Deborah collect than Cody?

These are questions from a math practice paper I did today. I am going to continue on it tomorrow, so I need the solutions by today.