ex7
a)548+30=578
4x139x15=556x15=8340
486+76=562
6x100x4=600x4=2400
70+405=475
350:50x9=7x9=63
b)170+135=305
850:50x3=17x3=51
(170+45)x3=215x3=645
21-15=6
42:2=21
1260:15=84
ex 8
a)[(430-80x4)+35]:5=
[(430-320)+35]:5=
[110+35]:5=
145:5=29
b)[720-(396-8x34):2]:2=
[720-(396-272):2]:2=
[720-124:2]:2=
[720-62]:2=
658:2=329
c)[1+(2+3x4)x5+4]:3-2x1=
[1+14x4]:3-2=
[1+56]:3-2=
57:3-2=19-2=17
d)(9+8-7)x6:(7+8-9)=
(17-7)x6:(15-9)=
10x6:6=60:6=10
e){[(1+2)x3x4x5:6-7-8]+9}x10=
{[2x3x4x5:6-7-8]+9}x10=
{[120:6-7-8]+9}x10=
{[20-7-8]+9}x10=
{5+9}x10=
14x10=140
f)[25+(4x65+2x70):100x175:100]x13=
[25+(260+140):100x175:100]x13=
[25+400:100x175:100]x13=
[25+4x175:100]x13=
[25+700:100]x13=
[25+7]x13=
32x13=416
