Tính nhanh

Tính nhanh
a, 2  3/7 x 19/5 + 17/5 x 1 2/7
b, (41,23 x 252 ) : 12
c, 1/3+5/7-9/19 /  3/6+15/14-27/38 +  2/5-4/9+8/11  /  3/5-3/6+12/11
d, 3/2x5 + 3/5x8 + 3/8x11+........+3/402x405