Alright so, I assume you know the equation for a rectangle which is Length times width.
But anyhow, if each inch equals 2.54 centimeters then you just have to multiply that by the inches given to get the equivalent measurement in centimeters.
Do as shown:
20 x 2.54 = 50.8 length)
16 x 2.54 = 40.64 (width)
Now let’s just plug in the values into the rectangle formula
A = w * l
A = 40.64 * 50.8
A = 2,064.512
And rounded that would be:
2064.5
I apologize if anything is incorrect.