[1+(1/3-1/4)]*72=72+72(1/3-1/4)=72+24-18=78
[1+(1/3-1/4)]*72=72+1/3×72-1/4×72=72+24-18=78
[1+(1/3-1/4)]*72=72+1/3*72-1/4*72=72+24-18=78
78
