Đáp án:

Giải thích các bước giải:

1. Determine the distance Ron walked in 30 minutes. Since Ron's speed is $$3.5 \text{ km/h}$$3.5 km/h, and 30 minutes is $$0.5 \text{ hours}$$0.5 hours, the distance Ron walked is $$3.5 \times 0.5 = 1.75 \text{ km}$$3.5×0.5=1.75 km

2. Calculate the distance Jake walked by subtracting the distance Ron walked from the total distance between them. So, Jake walked $$4 \text{ km} - 1.75 \text{ km} = 2.25 \text{ km}$$4 km−1.75 km=2.25 km

3. To find Jake's speed, divide the distance he walked by the time he walked. Since he walked for $$0.5 \text{ hours}$$0.5 hours, Jake's speed is $$\frac{2.25 \text{ km}}{0.5 \text{ hours}} = 4.5 \text{ km/h}$$0.5 hours2.25 km​=4.5 km/h

Therefore, Jake's speed is $$4.5 \text{ km/h}$$