7. Determine the best buy (cheaper deal) in each of the following, a. 3 kg of washing powder for \( \$ 15.60 \) or 4 kg for \( \$ 19.80 \) b. 2 kg of Pink Lady apples for \( \$ 5.20 \) or 3 kg of Granny Smith apples for \( \$ 840 \) c. 3.2 litres of apple juice for \( \$ 5.60 \) or 4 litres of apple juice for \( \$ 680 \) d. 0.8 GB of internet usage for \( \$ 16 \) or 1.2 GB for \( \$ 25.80 \) with different service providers

To find the best buy, let's break it down by calculating the cost per kilogram or per litre for each option. a. For the washing powder: - 3 kg for \( \$ 15.60 \): \( \frac{15.60}{3} = \$ 5.20 \) per kg. - 4 kg for \( \$ 19.80 \): \( \frac{19.80}{4} = \$ 4.95 \) per kg. **Best Buy: 4 kg for \$19.80** b. For the apples: - 2 kg of Pink Lady apples for \( \$ 5.20 \): \( \frac{5.20}{2} = \$ 2.60 \) per kg. - 3 kg of Granny Smith apples for \( \$ 840 \): \( \frac{840}{3} = \$ 280 \) per kg. **Best Buy: 2 kg of Pink Lady apples for \$5.20** c. For the apple juice: - 3.2 litres for \( \$ 5.60 \): \( \frac{5.60}{3.2} = \$ 1.75 \) per litre. - 4 litres for \( \$ 680 \): \( \frac{680}{4} = \$ 170 \) per litre. **Best Buy: 3.2 litres for \$5.60** d. For internet usage: - 0.8 GB for \( \$ 16 \): \( \frac{16}{0.8} = \$ 20 \) per GB. - 1.2 GB for \( \$ 25.80 \): \( \frac{25.80}{1.2} = \$ 21.50 \) per GB. **Best Buy: 0.8 GB for \$16** So, the best deals are: **a. 4 kg for \$19.80, b. 2 kg of Pink Lady apples for \$5.20, c. 3.2 litres for \$5.60, and d. 0.8 GB for \$16.**