12/[(4.3-2.38)*25]
=12/1.92*25
=12/12*0.16*25
=1/4
7.7*5.4+7.7+0.36*77
=7.7*(5.4+1+3.6)
=7.7*(10+1)
=77+7.7
=84.7
1/2+2/30*12.6
=1/2+1/30*6.3
=1/2+1/189
=(189+2)/378
=191/378