Answer :
How many miles the spaceship can travel in 19 seconds?
Using the linear model
y = 5x + 1
we assume that x correspond to the time in seconds and y to its distance in miles.
Then, we want to find y when
x = 19
(because we want to find the distance the space ship can travel in 19 seconds of time).
Then, we just replace x by 19:
y = 5x + 1
↓ Replacing x by 19
y = 5 · 19 + 1
↓ 5 · 19 = 95
y = 95 + 1
y = 96
Answer: the spaceship can travel 96 miles in 19 seconds