Verified answer

Bonjour,

a) 5,4/9 + 11,2/27

= (5,4 x 3) / (9 x 3) + 11,2/27

= 16,2/27 + 11,2/27

= 27,4/27

= (27,4 x 10) / (27 x 10)

= 274/270

= (2 x 137) / (2 x 135)

= 137/135

b) 23/18 - 2,1/6

= 23/18 - (2,1 x 3) / (6 x 3)

= 23/18 - 6,3/18

= 16,7/18

= (16,7 x 10) / (18 x 10)

= 167/180

c) 3/1,1 - 3/11

= (3 x 100) / (1,1 x 100) - (3 x 10) / (11 x 10)

= 300/110 - 30/110

= 270/110

= (10 x 27) / (10 x 11)

= 27/11

d) 1/2,5 + 1/7,5

= (1 x 30) / (2,5 x 30) + (1 x 10) / (75 x 10)

= 30/75 + 10/75

= 40/75

= (5 x 8) / (5 x 15)

= 8/15.