Final answer:
Big Time Builders works at a faster rate, building tunnels at a rate of 21 meters per week.
Step-by-step explanation:
To determine which construction company works at a faster rate, we can compare the rates at which each company builds tunnels. The rate at which Big Time Builders builds tunnels is 84 meters per 4 weeks, which can be simplified to 21 meters per week. The rate at which Goldstar Construction builds tunnels is given by the equation y = 19x, where y represents the length of tunnel in meters and x represents the number of weeks. To determine the rate, we can divide the length by the number of weeks, so the rate for Goldstar Construction is 19 meters per week. Comparing the two rates, we can see that Big Time Builders works at a faster rate, building tunnels at a rate of 21 meters per week.