Exercice 69 page 90 Nathan 3 emes svppp

bonjour

( 2/3 : 5/6) - 2/5

= ( 2 /3 * 6/5)  - 2 /5

=  12 /15 - 2/5

=  12/15 - 6/15

=  6 /15 = 2/5

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

=  ( - 3/4 + 2/4) : ( 4/10 - 25/10)

=  - 1 /4 :  - 21/10

= - 1/4 * - 10/21

=  10/ 84

=  5/42