1) 3 1/4+6,4-7,5= 3,25+6,4-7,5=2,15
2) 2/11 * (14 1/3+2 1/6) = 3
14 1/3 + 2 1/6 = 16 + 1/3 + 1/6 = 16 + 1·2/3·2 + 1·1/6·1 = 16 + 2/6 + 1/6 = 16 + (2 +1)/6 = 16 3 6 = 16 1/2
2/11*16 1/2=2/11*33/2= 33/11=3
3) 16.5 : 2.745 - 1/19 × 57=16500:2745-(1·57)/19=1100/183-57/19=6 2/183 - 3 = 3 2/183