[plt-scheme] HtDP - Relational Operators

A clause in an example function from Chapter 25 evaluates to this --

(<= 0 10 100).

How can relational operators consume three arguments? What is the
order of evaluation? (is 0 less than or equal to 10 and is 10 less
than or equal to 100?)

Link to problem: http://www.htdp.org/2003-09-26/Book/curriculum-Z-H-32.html#node_sec_25.1

Thanks!
Dave Yrueta