Answer:
....we calculate the area of rectangles
1st rectangle: 3k*3=9k
2nd rectangle: 6(k+3)= 6k+18
the 2 rectangles have the same area,
we write :
9k=6k+18
we solve to find the value of k
9k=6k+18
9k-6k=18
3k=18
k = 18/3 =6
the value of k: 6
Explanation: