Find the total cost when p = 80 pages and c = 120 copies. (b) If a shopkeeper marks an article 30% above its cost price and sells it at GH¢162.50, what is his cost price?

Here are the solutions to questions 7, 8, and 9.

7. (a) Find the total cost when $p = 80$ pages and $c = 120$ copies.

Step 1: Use the given formula for the total cost $C$.

$$C = 0.03pc + 50$$

Step 2: Substitute the given values $p=80$ and $c=120$ into the formula.

$$C = 0.03 \times 80 \times 120 + 50$$

Step 3: Perform the multiplication and addition.

$$C = 2.4 \times 120 + 50$$ $$C = 288 + 50$$ $$C = 338$$

The total cost is GH¢ 338.

$$\boxed{C = \text{GH}\cent 338}$$

7. (b) If a shopkeeper marks an article 30% above its cost price and sells it at GH¢162.50, what is his cost price?

Step 1: Let the cost price be $CP$. The selling price ($SP$) is the cost price plus a 30% mark-up.

$$SP = CP + 0.30 \times CP$$ $$SP = 1.30 \times CP$$

Step 2: Substitute the given selling price $SP = \text{GH}\cent 162.50$ into the equation.

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