Question

hepl me 

Answer 1

1.

$=15+37+52-37-17=(15+52-17)+(37-37)=(67-17)+0=50$

2.

$=(38+14)-42-(25-15-27)$

$=52-42-(10-27)=10-(10-27)=10-10+27=27$

3.

$=-21+32+12-32=(12-21)+(32-32)=-9+0=-9$

4.

$-12-21+23-23+21-10=-12+(-21+21)+(23-23)-10$

$=-12+0+0-10=-12-10=-(12+10)=-22$

Answer 2

5.

$=57-725-605+53=(57+53)-(725+605)$

$=110-1330=-(1330-110)=-1220$

6.

$=(55+45)+15-15+55-45$
$=100+(15-15)+(55-45)=100+0+10=110$

7.

$=35+75+345-35-75$

$=(35-35)+(75-75)+345=0+0+345=345$

8.

$=2002-79+15+79-15$

$=2002+(-79+79)+(15-15)=2002+0+0=2002$
9.

$=-515+80-91-2003-80+91=-515+(80-80)+(-91+91)-2003$

$=-515+0+0-2003=-(515+2003)=-2518$