Answer: a plumber earns $50 each day and a helper earns $30 each day.
Step-by-step explanation:
Let x represent the amount that a plumber earns in a day.
Let y represent the amount that a helper earns in a day.
One day, four plumbers and five helpers earned $350. This means that
4x + 5y = 350 - - - - - - - - - - -1
At the same rate of pay, another group of five plumbers and six helpers earned $430. This means that
5x + 6y = 430 - - - - - - - - - - - - 2
Multiplying equation 1 by 5 and equation 2 by 4, it becomes
20x + 25y = 1750
20x + 24y = 1720
Subtracting, it becomes
y = 30
Substituting y = 30 into equation 1, it becomes
4x + 5 × 30 = 350
4x + 150 = 350
4x = 350 - 150
4x = 200
x = 200/4 = 50
