a) 2/5 x 150 - (459-72) : 9 +11
2/5 x 150 - 387 : 9 + 11
= 60 - 43 + 11
= 28 
b) 2,14 x 68 +32 x 2,14 +1806
= 2,14 x (68 + 32) + 1806
= 2,14 x 100 + 1806 
= 214 + 1806 
= 2020 
c) 2,35 : ( y - 15,3) = 1/2
y - 15,3 = 2,35 : 1/2 
y - 15,3 = 4,7
y = 4,7 + 15,3
y = 20
d) (1 1/25 + 14/9 + 17/5) - ( 2/25 + 5/9 + 40%)          
= ( 26/25 + 14/9 + 17/5) - (2/25 + 5/9 + 2/5
= 26/25 + 14/9 + 17/5 - 2/25 - 5/9 - 2/5
= (26/25 - 2/25) + (14/9 - 5/9) + (17/5 - 2/5)
= 24/25 + 1 + 3 
= 124/25