Per treure els denominadors, es calcula el seu mcm

i s'escriuen fraccions equivalents: 

«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«mfrac mathcolor=¨#00007F¨»«mrow»«mn mathvariant=¨bold¨»2«/mn»«mi mathvariant=¨bold¨»x«/mi»«mo mathvariant=¨bold¨»+«/mo»«mn mathvariant=¨bold¨»1«/mn»«/mrow»«mn mathcolor=¨#7F007F¨ mathvariant=¨bold¨»4«/mn»«/mfrac»«mo mathvariant=¨bold¨ mathcolor=¨#00007F¨»+«/mo»«mfrac mathcolor=¨#00007F¨»«mrow»«mn mathvariant=¨bold¨»3«/mn»«mi mathvariant=¨bold¨»x«/mi»«mo mathvariant=¨bold¨»-«/mo»«mn mathvariant=¨bold¨»5«/mn»«/mrow»«mn mathcolor=¨#7F007F¨ mathvariant=¨bold¨»6«/mn»«/mfrac»«mo mathvariant=¨bold¨ mathcolor=¨#00007F¨»=«/mo»«mfrac mathcolor=¨#00007F¨»«mrow»«mi mathvariant=¨bold¨»x«/mi»«mo mathvariant=¨bold¨»+«/mo»«mn mathvariant=¨bold¨»4«/mn»«/mrow»«mn mathcolor=¨#7F007F¨ mathvariant=¨bold¨»10«/mn»«/mfrac»«/math»

mcm(4,6,10) = 60.

Com que 60:4=15, 60:6=10, i  60:10=6:

«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«mfrac mathcolor=¨#00007F¨»«mrow»«mn mathvariant=¨bold¨ mathcolor=¨#FF0000¨»15«/mn»«mfenced»«mrow»«mn mathvariant=¨bold¨»2«/mn»«mi mathvariant=¨bold¨»x«/mi»«mo mathvariant=¨bold¨»+«/mo»«mn mathvariant=¨bold¨»1«/mn»«/mrow»«/mfenced»«/mrow»«mn mathvariant=¨bold¨ mathcolor=¨#007F00¨»60«/mn»«/mfrac»«mo mathvariant=¨bold¨ mathcolor=¨#00007F¨»+«/mo»«mfrac mathcolor=¨#00007F¨»«mrow»«mn mathvariant=¨bold¨ mathcolor=¨#FF0000¨»10«/mn»«mfenced»«mrow»«mn mathvariant=¨bold¨»3«/mn»«mi mathvariant=¨bold¨»x«/mi»«mo mathvariant=¨bold¨»-«/mo»«mn mathvariant=¨bold¨»5«/mn»«/mrow»«/mfenced»«/mrow»«mn mathvariant=¨bold¨ mathcolor=¨#007F00¨»60«/mn»«/mfrac»«mo mathvariant=¨bold¨ mathcolor=¨#00007F¨»=«/mo»«mfrac mathcolor=¨#00007F¨»«mrow»«mn mathvariant=¨bold¨ mathcolor=¨#FF0000¨»6«/mn»«mfenced»«mrow»«mi mathvariant=¨bold¨»x«/mi»«mo mathvariant=¨bold¨»+«/mo»«mn mathvariant=¨bold¨»4«/mn»«mo mathvariant=¨bold¨»)«/mo»«/mrow»«/mfenced»«/mrow»«mn mathvariant=¨bold¨ mathcolor=¨#007F00¨»60«/mn»«/mfrac»«/math»

15(2x+1)+10(3x-5)=6(x+4)