I don't understand this​

We can start off by knowing that perimeter is all the sides added together. That means that (2 1/2 x 2) + ((2 1/2 + x) x 2) = 19.

It would be easier to make this into decimals. 2 1/2 is the same as 2.5. Multiply this by 2 and you get 5.

Now you can do 19 - 5 = 14.

This means the other 2 sides have to equal 14 so you write an equation.

2(2.5 + x) = 14.

When you simplify, you get 5 + 2x = 14.

Subtract 5 from both sides and you get 2x = 9.

Solve for x and you get x = 4.5.

Your answer is x = 4.5