7,8*(4/13)-61,5:13²/₃+198,8
1) 7,8*(4/13)=7⁴/₅*(4/13)=(39/5)*(4/13)=39*4/(5*13)=12/5.
2) 61,5:13²/₃=61¹/₂:13²/₃=(123/2):(41/3)=123*3/(2*41)=9/2.
3) 12/5+9/2+198,8=12/5+9/2+198⁴/₅=12/5+9/2+994/5=1006/5+9/2=
=(1006*2+9*5)/10=(2012+45)/10= 2057/10=205,7.