Bonjour
1)
A = 2/3 + 5/3 x 1/15
A = 2/3 + 5/45
A = (2 x 3) / (3 x 3) + (5 x 1) / (5 x 9)
A = 3/9 + 5/9
A = 8/9
B = (1 - 3/7) : 12/5
B = [(1 x 7) / (1 x 7) - 3/7] : 12/5
B = (7/7 - 3/7) : 12/5
B = 4/7 : 12/5
B = 4/7 x 5/12
B = 20/84
B = (4 x 5) / (4 x 21)
B = 5/21
C = 9/2 : 3
C = 9/2 x 1/3
C = 9/6
C = (3 x 3) / (3 x 2)
C = 3/2
D = (3/4 + 3) : (1/2 + 2)
D = [3/4 + (3 x 4) / (1 x 4)] : [1/2 + (2 x 2) / (1 x 2)]
D = (3/4 + 12/4) : (1/2 + 4/2)
D = 15/4 : 5/2
D = 15/4 x 2/5
D = 30/20
D = (10 x 3) / (10 x 2)
D = 3/2
2)
a. 2/5 + 1
= 2/5 + (1 x 5) / (1 x 5)
= 2/5 + 5/5
= 7/5
b. 3/4 x 2/5
= 6/20
= (2 x 3) / (2 x 10)
= 3/10
c. 1/3 x 2/5 + 2/5
= 2/15 + (2 x 3) / (5 x 3)
= 2/15 + 6/15
= 8/15
d. 3/5 : 2/5
= 3/5 x 5/2
= 15/10
= (5 x 3) / (5 x 2)
= 3/2
e. (3/2 - 10/6) : (2/7 + 1/3)
= [(3 x 3) / (2 x 3) - 10/6] : [(2 x 3) / (7 x 3) + (1 x 7) / (3 x 7)]
= (9/6 - 10/6) : (6/21 + 7/21)
= - 1/6 : 13/21
= - 1/6 x 21/13
= - 21/78
= (3 x - 7) / (3 x 26)
= - 7/26
f. 3 - 5 : (1 + 1/3)
= 3 - 5 : [(1 x 3) / (1 x 3) + 1/3]
= 3 - 5 : (3/3 + 1/3)
= 3 - 5 : 4/3
= 3 - 5 x 3/4
= (3 x 4) / (1 x 4) - 15/4
= 12/4 - 15/4
= - 3/4.
