Concerns about the economy pushed oil prices lower on Monday. West Texas Intermediate, the U.S. benchmark crude, gave up 85 cents to end at $102.46 per barrel. Brent crude, which is used to price oil imported by U.S. refineries, fell by 76 cents to finish at $122.67 per barrel. The U.S. economy added just 120,000 jobs in March -- half as much as each of the previous three months. The government reported the disappointing data on Friday, but Monday was the first day oil markets could react. Stocks also fell. Analysts said the slower pace of hiring could be a symptom of a weakening economy. It also hints at a slowdown in gasoline usage. Iran also weighed on oil markets. OPEC's No. 2 oil producer agreed to hold talks about its nuclear program with the West starting Friday. That eased fears of a prolonged standoff that could further squeeze world oil supplies. Already, international sanctions have forced some of the biggest importers of Iranian oil to find other sources. Renewed negotiations could lead to an agreement that lifts those sanctions. The talks also reduce the risk, for now, that Iran will try to choke off exports from other oil producers by closing shipping routes out of the Persian Gulf. Concerns about a prolonged standoff with Iran have added about $13 to $14 to the price of a barrel of oil, independent analyst Jim Ritterbusch said. Oil should fall further if Iran works with the West, although Ritterbusch expects the price to remain elevated "for months to come." "As long as the regime stays in place, the nuclear threat is always going to be there," he said. In the U.S., gasoline prices fell by about a penny over the weekend to $3.927 per gallon, according to auto club AAA, Wright Express and Oil Price Information Service. Pump prices have eased after nearing $3.94 a gallon last week. Experts still say that prices could peak this month between $4.25 and $4.35 per gallon. In other energy trading, heating oil fell by 2.33 cents to $3.1459 per gallon while gasoline futures fell by 4.38 cents to finish at $3.2967 per gallon. Natural gas added 1.8 cents to end at $2.107 per 1,000 cubic feet.