Answer:
7 = 49 ÷ r
Explanation:
To find the equation that is true when r = 7, we need to find a number after the equals sign that is a multiple of 7.
Multiples of 7:
7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77...
Therefore, the only answer option in which the number after the equals sign is a multiple of 7 is:
7 = 49 ÷ r
To prove this, input r = 7 into each of the equations:
6 = 30 ÷ r
⇒ 6 = 30 ÷ 7
⇒ 6 ≠ 4.285... ← incorrect!
7 = 54 ÷ r
⇒ 7 = 54 ÷ 7
⇒ 7 ≠ 7.714... ← incorrect!
7 = 49 ÷ r
⇒ 7 = 49 ÷ 7
⇒ 7 = 7 ← correct!
9 = 72 ÷ r
⇒ 9 = 72 ÷ 7
⇒ 9 ≠ 10.285... ← incorrect!