Answer the following question, with explanation first.
Barry wants to make a huge salad using only cucumbers and tomatoes. He will use a total of 280 pieces of vegetables. If there are thrice as many tomatoes as cucumbers, how many cucumbers will be used in the salad?

70
Let c be the number of cucumbers and t the number of tomatoes.

The total is the sum of the number of cucumbers and that of tomatoes, which is c + t = 280 piece of vegetables.

Since there are thrice as many tomatoes as cucumbers, this means c = t / 3.

Therefore 3 * c = t.

The sum will therefore be c + 3 * c = 280 pieces of vegetables.

This means that 4 * c = 280 vegetables.

Therefore c = 280 / 4 = 70 cucumbers.

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Final answer: 70