⁷P_r = 210 and ⁷C_r = 35 then what is the value of r?

Question: ⁷P_r = 210 and ⁷C_r = 35 then what is the value of r?
​
​​​​Solution:
​Given that,
​⁷P_r = 210 and ⁷C_r = 35
​
​We know that,
​ⁿP_r​ = r! × ⁿC_r​
​⇒ 210 = r! × 35
​⇒ ​r! = 210/35
​ ​⇒ r! = 6
​⇒ ​r! = 3!
∴ ​r = 3