Peter has 19 – 7 = <<19-7=12>>12 years of experience.
Robert has 12 – 4 = <<12-4=8>>8 years of experience.
Mike has 8 – 2 = <<8-2=6>>6 years of experience.
Tom has 2 * 8 = <<2*8=16>>16 years of experience.
Roger has 12 + 8 + 6 + 16 = <<12+8+6+16=42>>42 years of experience.
Roger has to work another 50 – 42 = <<50-42=8>>8 years before he retires.
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