The statement
a is p percent of b
represents the proportion
where b is base, a is a part of the base and
is the percent.
Let x is the side length of a smaller square and y is the side length of a larger square.
\The word
the side length x of a smaller square is 40% of the the side length y of a larger square
represent the proportion
.
Simplification of proportion is
.
The area formula of a square is
.
The area of smaller square is
and the area of larger square is
.
The word
the ratio of area of a smaller square to area of a larger square
represent the proportion
.
Substitute the value of
in the proportion
.

To calculate the percentage, multiply the number by 100.
\Therefore 
Cancel common terms.
\

Multiply each side by term
.

Cancel common terms.
\
.
The equation
represent the words
the area of a smaller square is 16% of the area of the larger square
.
No, the area of a smaller square does not 40% of the area of the larger square
.