Answer:
20
Step-by-step explanation:
This sequence follows a pattern of doubling then subtracting by two. The last action was 12 to 10, which is subtracting by two, so the next must be multiplying by 2.
You can solve by using Pythagoras theorem.
Let the longest side be c.
a^2 + b^2 = c^2
If this holds, it is a right angle.
But, 3.5^2 + 4.5^2 is not equal to 5.5^2.

×

To multiply, you multiply across. So it would be 3×1=3 and 10×6=60
Which will result in

but in order to simplify it, you find a common factor. The common factor is 3. 3÷3=1 and 60÷3=20
The answer is