Monthly basic salary = 4,500
Rate of Commission earned above 50,000 = 5% or 0.05
Sales = 285,000
x = Salesman's earnings
Equation:
x = [(285,000 - 50,000) × 0.05] + 4,500
x = [(235,000) × 0.05] + 4,500
x = (11,750) + 4,500
x = 16,250
ANSWER: The salesman earned Php 16,250 when his sales mounted to 285,000.