The calculation can be made true by choosing cards with the numbers 6 (multiple of 3) and 8 (multiple of 4), which sum up to 14 (multiple of 7).
To solve the problem given, we need to find three numbers such that one is a multiple of 3, another is a multiple of 4, and their sum is a multiple of 7. We can begin by listing small multiples of 3 and 4 to find a pair that adds up to a multiple of 7. For the sake of the example, let's choose:
Multiple of 3 could be 6 (2×3)
Multiple of 4 could be 8 (2×4)
Adding these together, we get 6 + 8 = 14, which is coincidently a multiple of 7 (2×7).
Therefore, the cards can be arranged as follows to make the calculation true:
Multiple of 3 = 6
Plus Multiple of 4 = 8
Equals Multiple of 7 = 14