7. Nancy buys 15 m of ribbon. Her sister buys 6 m less ribbon but pays twice as much per metre. Together they pay R66. What is the price per metre of each type of ribbon? 8. Sam bought some apples at 60 c each and sold all but 5 of them at R1,00 each. If he made a profit of R5,00, how many apples did he buy? 9. If you are allowed to choose 20 coins from a collection of 50 cent coins and R1 coins, how many coins must be R1 coins if the total value is R15?

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### Problem 7
**Known Conditions:**
- Nancy buys 15 m of ribbon.
- Her sister buys 6 m less, so she buys $$ 15 - 6 = 9 $$ m of ribbon.
- The sister pays twice as much per metre as Nancy.
- Together they pay R66.

Let $$ p $$ be the price per metre of Nancy's ribbon. Then the price per metre of her sister's ribbon is $$ 2p $$.

**Calculating Total Cost:**
- Cost for Nancy: $$ 15p $$
- Cost for her sister: $$ 9 \times 2p = 18p $$

The total cost is:
$$
15p + 18p = 66
$$
$$
33p = 66
$$
$$
p = 2
$$

**Price per Metre:**
- Nancy's price per metre: R2
- Sister's price per metre: $$ 2p = 4 $$

### Problem 8
**Known Conditions:**
- Sam bought apples at 60 cents each.
- He sold all but 5 at R1.00 each.
- He made a profit of R5.00.

Let $$ x $$ be the number of apples Sam bought.

**Calculating Costs and Sales:**
- Cost of apples: $$ 0.60x $$
- Number of apples sold: $$ x - 5 $$
- Revenue from selling apples: $$ 1.00(x - 5) $$

**Profit Equation:**
Profit is given by:
$$
\text{Revenue} - \text{Cost} = 5
$$
Substituting the values:
$$
1.00(x - 5) - 0.60x = 5
$$
Expanding and simplifying:
$$
x - 5 - 0.60x = 5
$$
$$
0.40x - 5 = 5
$$
$$
0.40x = 10
$$
$$
x = 25
$$

**Number of Apples Bought:**
Sam bought 25 apples.

### Problem 9
**Known Conditions:**
- Total coins chosen: 20
- Total value: R15
- Coins are either 50 cent coins or R1 coins.

Let $$ x $$ be the number of R1 coins. Then the number of 50 cent coins is $$ 20 - x $$.

**Calculating Total Value:**
The total value can be expressed as:
$$
1.00x + 0.50(20 - x) = 15
$$
Expanding and simplifying:
$$
x + 10 - 0.50x = 15
$$
$$
0.50x + 10 = 15
$$
$$
0.50x = 5
$$
$$
x = 10
$$

**Number of R1 Coins:**
There must be 10 R1 coins.

### Summary of Answers:
1. Nancy's price per metre: R2; Sister's price per metre: R4.
2. Sam bought 25 apples.
3. There must be 10 R1 coins.
- **Problem 7:** Nancy's ribbon costs R2 per metre, her sister's costs R4 per metre. - **Problem 8:** Sam bought 25 apples. - **Problem 9:** There must be 10 R1 coins.

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