90-(72-70)=90-2=88

42+(33+7)=42+40 =82

78-(36-6)=78-30=48

75-20+40 =55+40=95

88-8+60 =80+60 = 140

70-(48+2)=70-50=20

(45- 17)+(9-3)=28+6=34, (45- 17)+(9-6)=28+3=3 1, (45- 18)+(9-3)=27+6=33

(45- 18)+(9-6)=27+3=30, (45-27)+(9-3)= 18+6=24, (45-27)+(9-6)= 18+3=2 1

(45-28)+(9-3)= 17+6=23, (45-28)+(9-6)= 17+3=20, (46- 17)+(8-3)=29+5=34

(46- 17)+(8-5)=29+3=32, (46- 19)+(8-3)=27+5=32, (46- 19)+(8-5)=27+3=30

(46-27)+(8-3)= 19+5=24, (46-27)+(8-5)= 19+3=22, (46-29)+(8-3)= 17+5=22

(46-29)+(8-5)= 17+3=20, (54- 16)+(9-2)=38+7=45, (54- 16)+(9-7)=38+2=40

(54- 18)+(9-2)=36+7=43, (54- 18)+(9-7)=36+2=38, (54-36)+(9-2)= 18+7=25

(54-36)+(9-7)= 18+2=20, (54-38)+(9-2)= 16+7=23, (54-38)+(9-7)= 16+2= 18

(57- 18)+(6-2)=39+4=43, (57- 18)+(6-4)=39+2=4 1, (57- 19)+(6-2)=38+4=42

(57- 19)+(6-4)=38+2=40, (57-38)+(6-2)= 19+4=23, (57-38)+(6-4)= 19+2=2 1

(57-39)+(6-2)= 18+4=22, (57-39)+(6-4)= 18+2=20, (63- 15)+(9-2)=48+7=55

(63- 15)+(9-7)=48+2=50, (63- 18)+(9-2)=45+7=52, (63- 18)+(9-7)=45+2=47

(63-45)+(9-2)= 18+7=25, (63-45)+(9-7)= 18+2=20, (63-48)+(9-2)= 15+7=22

(63-48)+(9-7)= 15+2= 17, (64-25)+(8- 1)=39+7=46, (64-25)+(8-7)=39+ 1=40