In 18 hours, 42 trains pass near Emma's house. How many trains pass near her house in 12 hours?

To determine how many trains pass near Emma's house in 12 hours, we first need to find the rate at which the trains pass by her house. Starting with the information given, in 18 hours, 42 trains pass.

To find the rate of trains passing per hour, divide the total number of trains by the total number of hours:

[

\text{Rate of trains per hour} = \frac{42 \text{ trains}}{18 \text{ hours}} = \frac{42}{18} = \frac{7}{3} \text{ trains per hour}

]

Next, to find out how many trains pass in 12 hours, we multiply the hourly rate by 12:

[

\text{Trains in 12 hours} = \left(\frac{7}{3} \text{ trains per hour}\right) \times 12 \text{ hours}

]

Simplifying this calculation:

[

\text{Trains in 12 hours} = \frac{7 \times 12}{3} = \frac{84}{3} = 28 \text{ trains}

]

Thus, the result shows that in 12 hours, 28 trains pass