Answer:
Ratio of the corresponding sides of rectangle 
➾ 10 : 3
Areas will by in the ratio of 10² : 3² 
➾ 100 : 9
Explanation : 
let first rectangles sides be 10 l and 10 b ➾ The area will be 100 × l × b
So second rectangles sides be 3 l and 3b 
➾ The area will be 9 × l × b
So the ratio of areas 
➾100lb : 9lb 
➾ 100 : 9