Step-by-step explanation:
[tex]7(7 + 3k) = 217 \\ \\ 7 \times 7 + 7 \times 3k = 217 \\ \\ 49 + 21k = 217 \\ 21k = 217 - 49 \\ 21k = 168 \\ \\ k = \frac{168}{21} \\ \\ \huge \red{ \boxed{ k = 8}}[/tex]
Answer: k = 8
distribute the 7
49 + 21k = 217
subtract 49
21k = 168
divide by 21
k = 8
to check your answer:
plug in value of k in equation
7(7+24) = 217
49 + 168 = 217
217 = 217
