During a tunnel construction project, engineers used explosives to excavate partway into a mountain. but due to time constraints and environmental concerns, they later introduced a tunnel boring machine (tbm) to excavate the rest of the tunnel. the length y of the completed tunnel (in feet) is based on the number of days x since the tbm started working. the length can be calculated using the equation y = 25x + 225. what does the y-intercept represent in this scenario? the length of the tunnel completed after the tbm was introduced the length of the tunnel completed before the tbm was introduced the number of days on the construction project after the tbm was introduced the number of days on the construction project before the tbm was introduced