Verified answer

2 1/2 = 2 + 1/2 = 2*2/2 + 1/2 = (4 + 1)/2 = 5/2

3 - 5/2 + 1/4

mmc = 4

3 = 12/4

5/2 = 10/4

1/4 = 1/4

12/4 - 10/4 + 1/4 = (12 - 10 + 1)/4 = (13 - 10)/4 = 3/4

pronto

3- 2 1/2 + 1/4 ........ mmc = 4 . . . 2 1/2 = 5/2

4: 1 x 3 = 12

4 : 2 x 5 = 10

4 : 4 x 1 = 1

fica entao:

12 - 10 + 1 . . . 3

--------------- = -------

. . . 4 . . . . . . . 4

3- 2 1/2 + 1/4

3- (2+1/2) + 1/4

3- (5/2) + 1/4 mmc 4

(12-10+1) /4 = 3/4