In similar figures, the ratio between corresponding sides are the same.
Simplify the two to see that they are equal.
The top and bottom of the left fraction are divisible by 5.
The top and bottom of the right fraction are divisible by 7.
Of course, the dimensions of that third picture would have to be this fraction.
Let's test these answers.
⇒ A is not a solution
⇒ B is the solution
(divide the top and bottom by 6)
Simplify the two to see that they are equal.
The top and bottom of the left fraction are divisible by 5.
The top and bottom of the right fraction are divisible by 7.
Of course, the dimensions of that third picture would have to be this fraction.
Let's test these answers.
(divide the top and bottom by 6)