a) 45.37 + 45.63 - 100

45.(37+63)–10045.(37+63)–100

45.100–10045.100–100

 100.(45–1)100.(45–1)

100.44=4400
b)=148.9−9.48
=9.(148−48)
=9.100=900

c) 307-[ ( 180-160) : 2² + 9] : 2

=307-[ 20 : 4 + 9] : 2

=307-[ 5+ 9] : 2

=307-14 : 2

=307-7

=300
 

12+3.{90:[39-(2³-5)²]}

=12+3.{90:[39-(8-5)²]}

=12+3.{90:[39-3²]}

=12+3.{90:[39-9]}

=12+3.{90:30]}

=12+3.3

=12+9
=21