Answer:
"time and a half" workers were paid 50% more per day
Explanation:
You want to know the relative daily pay rates of laborers making time and a half versus those who were not. 4 getting time and a half and 20 not earned a total of $2080, while 2 getting time and a half and 15 not earned a total of $1440.
Setup
We can let x and y represent the daily pay of time and a half workers, and those not earning time and a half. The two payrolls can be described by ...
4x +20y = 2080
2x +15y = 1440
Solution
Subtracting the first equation from 2 times the second, we have ...
2(2x +15y) -(4x +20y) = 2(1440) -(2080)
10y = 800 . . . . . . . simplify
y = 80 . . . . . . . . . . divide by 10
2x +15(80) = 1440
2x = 240 . . . . . . . . . . subtract 1200
x = 120 . . . . . . . . divide by 2
Workers getting time and a half made $120 per day; workers not getting time and a half made $80 per day. Workers getting time and a half made half again as much as those who didn't: $40 per day more, or 50% more, or half-again as much.
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Additional comment
"Time and a half" means the pay is 50% more. That's what we see here. You don't need any math to say those getting time and a half were getting 50% more per day.