Answer:
11cm
Explanation:
Hi, I can help.
Now to find this it is just simple subtraction but you need to know what to look for.
Let us first imagine that the top rectangle sticking out doesn't exist. Lets focus on the bottom rectangle who has the dimensions of 6 and 18cm. We need to find the ? on the top of the rectangle.
Now lets add the top rectangle. Something important to remember is that the 5cm top lines up with the ? even though it is above it.
Also, the top and bottom of a rectangle is always to going to match up / be equal.
So the 5cm + ? is going to be equal to 16cm.
So how can we use this info to find the answer? We can actually look at the 16cm and 5cm. Since the 16cm and the 5 + ? are equal we can take the 16cm at the bottom and actually take away 5cm away from it to find the ?.
So :
16cm - 5cm = 11cm
So literally that is it.
11cm is your ?
I feel like I didn't do a great job explaining this so if you have any questions AT ALL please comment or message me and I will help you anywhere its needed. :)