The arrangement of the movie theater, supermarket and the beauty parlor form a right angled triangle with hypotenuse being the number of blocks between the supermarket and the parlor.
The legs of the triangle are 3 blocks and 4 blocks.
The question is about finding the hypotenuse.
Therefore,
Hypotenuse = Sqrt (3^2+4^2) = 5 blocks. The street is 5 blocks long.