Answer:
Li worked for 19 hours.
Step-by-step explanation:
Let's call x the number of hours that Vic worked, y the number of hours that Sam worked, and z the number of hours that Li worked.
They all work for 52 hours, so:
x + y + z = 52
Sam worked 3 fewer hours than Vic and 4 fewer than Li, so:
y = x - 3 or y + 3 = x
y = z - 4 or y + 4 = z
So, we can replace x and z on the first equation and solve for y as:
(y + 3) + y + (y + 4) = 52
y + 3 + y + y + 4 = 52
3y + 7 = 52
3y + 7 - 7 = 52 - 7
3y = 45
3y/3 = 45/3
y = 15
Then, replacing y by 15, we can calculate the value of x and z as:
x = y + 3
x = 15 + 3
x = 18
z = y + 4
z = 15 + 4
z = 19
Therefore, Li worked for 19 hours.