Given:
Tom's earnings: x
Jan's earnings: 2x - 150
Total earnings: 1380
x + 2x - 150 = 1380
3x = 1380 + 150
3x = 1530
3x/3 = 1530/3
x = 510
Tom's earnings: x = 510
Jan's earnings: 2x - 150 = 2(510) - 150 = 1,020 - 150 = 870
total earnings: 1,380
510 + 870 = 1,380
1,380 = 1,380