a: =72,5*13,5-61,5-13,6-13,6
=978,75-61,5-27,2
=890,05
b: =132,5(2+4+8+6)
=132,5*20=2650
`132,5xx2+132,5xx4+132,5:0,125+132,5xx6`
`=132,5xx2+132,5xx4+132,5:1/8+132,5xx6`
`=132,5xx2+132,5xx4+132,5xx8+132,5xx6`
`=132,5xx(2+4+8+6)`
`=132,5xx20`
`=2650`
`72,25xx13,5-13,6-61,5-9,3-4,3`
`=145xx0,5xx0,5xx27-(13,6+61,5+9,3+4,3)`
`=0,25xx145xx27-88,7`
`=36,25xx27-88,7`
`=978,75-88,7`
`=890,05`