PW(10%)A and PW(10%)B were calculated as $9,738 and $10,131 respectively, with a difference of $393. PW(10%)C and PW(10%)D were calculated as -$477,077 and -$463,607 respectively, with a difference of $13,470. The document discusses determining an appropriate study period to compare multiple equivalent alternatives, noting the study period should match the equal lives of the alternatives or be at least as long as the longest life if they are unequal. Equivalent worth methods like present worth can be used to directly compare alternatives with equal lives.