Question

what does the idiom in this text suggest?
cell phones once cost an arm and a leg, but today the majority of people can afford them.
cell phones were once very expensive.
cell phones were once popular items to trade.

Explanation:

The idiom "cost an arm and a leg" is a common English expression that means something is extremely expensive. The sentence contrasts this past cost with the fact that most people can afford cell phones now, so the idiom refers to the high former price of cell phones.

Answer:

Cell phones were once very expensive.