The problem consists of two sub-problems: (1) If 1 meter of ribbon costs 240 yen, what is the cost of $\frac{3}{4}$ meters of ribbon? (2) If 1 liter of oil weighs $\frac{7}{8}$ kg, what is the weight of $\frac{4}{5}$ liters of oil?

1. Problem Description

The problem consists of two sub-problems:

(1) If 1 meter of ribbon costs 240 yen, what is the cost of $\frac{3}{4}$ meters of ribbon?

(2) If 1 liter of oil weighs $\frac{7}{8}$ kg, what is the weight of $\frac{4}{5}$ liters of oil?

2. Solution Steps

(1) The cost of $\frac{3}{4}$ meters of ribbon can be found by multiplying the cost per meter by the length of the ribbon.

Cost = (Cost per meter) * (Length in meters)

Cost = $240 \times \frac{3}{4}$

$240 \times \frac{3}{4} = \frac{240 \times 3}{4} = \frac{720}{4} = 180$

The cost of $\frac{3}{4}$ meters of ribbon is 180 yen.

(2) The weight of $\frac{4}{5}$ liters of oil can be found by multiplying the weight per liter by the volume of the oil.

Weight = (Weight per liter) * (Volume in liters)

Weight = $\frac{7}{8} \times \frac{4}{5}$

$\frac{7}{8} \times \frac{4}{5} = \frac{7 \times 4}{8 \times 5} = \frac{28}{40} = \frac{7}{10}$

The weight of $\frac{4}{5}$ liters of oil is $\frac{7}{10}$ kg.

3. Final Answer

(1) 180

(2) $\frac{7}{10}$