# Study plan: Percentages for bookkeeping

- Goal: Understand percentages properly for the bookkeeping course quiz, especially “what percent of 80 is 12” and percentage increase.
- Deadline: 2026-04-14
- Time available: 3 hours per week
- Starting point: Comfortable with 50% and 10% in head; gets lost with “what percent of 80 is 12” and percentage increase.

## Plan

| Session | Topic | Length | Source |
|---|---|---|---|
| 1 | Review percent basics and “percent means per hundred” | 30 min | Unit 2: percentages |
| 2 | Practice `part = percent × whole` for missing percent and missing part | 45 min | Unit 2: percentages |
| 3 | Learn percentage change with bookkeeping examples | 45 min | Unit 2: percentages |
| 4 | Mixed practice and error check | 45 min | Unit 2: percentages |
| 5 | Quiz simulation and final review | 15 min | Unit 2: percentages |

## Explanation: What percent of 80 is 12?

Percent means “per hundred.” When we ask “what percent of 80 is 12,” we are asking: 12 equals what number out of 100 compared to 80. The course note gives `part = percent × whole`. Here 12 is the part, 80 is the whole, and the percent is unknown. Divide the part by the whole, then express it as per hundred.

Worked example: What percent of 80 is 12?
`12 ÷ 80 = 0.15`
`0.15 × 100 = 15%`
So 12 is 15% of 80.

## Practice

1. What percent of 80 is 12?
2. Find 25% of 200.
3. 35 is what percent of 140?
4. A bookkeeping value rises from 500 to 650. What is the percentage increase?
5. A balance falls from 900 to 720. What is the percentage change?

## Answers (keep separate)

1. 15%
2. 50
3. 25%
4. 30%
5. -20%

## Progress notes

- Right: Already confident with 50% and 10%, so doubling and halving mental math is solid.
- Revisit: Percentage change sign interpretation; when a value falls, express it as a negative percent or clearly label it as a decrease.