A cura di: Alfredo Bochicchio

${[-12/5a^2b^2xx(-25/6a^3b^3)]:(5ab)^2}:[2/5xx(ab)^6:a^3b^3]$
${10a^5b^5:(25a^2b^2)}:[2/5xx(a^6b^6:a^3b^3]$
$10/25a^3b^3:2/5a^3b^3$
$2/5a^3b^3:2/5a^3b^3$
$1$