1. Square of 2004 - square of 2003, (3 2 / 9 + 9 2 / 3) * (except) (1 / 9 + 1 / 3) 3. 2.4 * (multiply) 20 and 3 / 5 + 33.1 * (multiply) 7.64, (2890 + 5 / 6 + 7 / 8 + 7 / 10) * (except) (5 / 6 + 7 / 8 + 7 / 10) eldest brother! Can you write out the idea and process?

1. Square of 2004 - square of 2003, (3 2 / 9 + 9 2 / 3) * (except) (1 / 9 + 1 / 3) 3. 2.4 * (multiply) 20 and 3 / 5 + 33.1 * (multiply) 7.64, (2890 + 5 / 6 + 7 / 8 + 7 / 10) * (except) (5 / 6 + 7 / 8 + 7 / 10) eldest brother! Can you write out the idea and process?

2004^2-2003^2
=(2004+2003)(2004-2003)
=4007
(3 + 2 / 9 + 9 + 2 / 3) / (1 / 9 + 1 / 3)
=(29/9+29/3)/（1/9+1/3）
=29（1/9+1/3）/（1/9+1/3）
=29
2.4 * (multiply) 20 and 3 / 5 + 33.1 * (multiply) 7.6
=12/5*103/5+331/10*38/5
=12*103/25+331*19/25
=（12*103+331*19）/25
=（1200+12*3+331*20-331）/25
=7525/25
=301
（2890+5/6+7/8+7/10）/（5/6+7/8+7/10）
=2890/（5/6+7/8+7/10）+1
=2890/[（100+7*15+7*12）/120+1
=2890*120/[100+7*（15+12）]+1
=2890*120/289+1
=1200+1
=1201