Bonsoir,
3/4 x 6/7 x 4/12
= 3x6x4/4x7x12
=3/7x2
=3/14
4/7 x 3/5
=12/35
3/4 x 6/17
=3x6/4x17
=3x3/2x17
=9/34
4/5 x 2/3 x 11/2
=4x2x11/5x3x2
=4x11/5x3
=44/15
11/6 x 3/14 x 8/21
=11x3x8/6x14x21
=11x3x2x2x2/3x2x2x7x21
=11x2/7x21
=22/147
7/8 x 24/35 x 5/9
=7x24x5/8x35x9
=7x8x3x5/8x5x7x9
=1/3
18/25 x 75/63
=9x2x5x5x3/5x5x7x3x3
=2x3/7
=6/7
22/39 x 13/11 x 5
=22x13x5/39x11
=10/3
11/21 x 5/3 x7
=11x5x7/21x3
=55/9
22/6 x 5/7 x 21/55
=22x5x21/6x7x55
=1