In the 1970s and 1980s, labor unions commonly negotiated wage contracts that had which guaranteed that their wages would keep up with inflation

The correct answer is : Cost-of-living adjustments

Explanation:

They are a contractual provision that salary increases will keep up with inflation. It is normally equal to the percentage increase in the Consumer Price Index. It refers to a change in a person's monthly retirement benefit as well. It also helps to calculate how the wages go up as living expenses go up.

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explanation:

with the profits from the european sales, merchants purchased europe's manufactured  goods, including tools and weapons. then the merchants shipped those manufactured  goods, along with the  american  sugar and rum, to west africa where they were bartered for  slaves.