Bonjour je n’arrives pas à faire cet exercice de maths

Bonjour

Calculer ;

L = -7/5 : (2/9 - 7/18)

L = -7/5 : [(2 x 2)/(9 x 2) - 7/18]

L = -7/5 : [4/18 - 7/18]

L = -7/5 : (-3/18)

L = -7/5 : (-3/(3 x 6))

L = -7/5 : -1/6

L = -7/5 x (-6)

L = 42/5

M = (4/5 + (-3/2)) : (-9/4 - 1/6)

M = [(4 x 2)/(5 x 2) - (3 x 5)/(2 x 5)] : [(-9 x 3)/(4 x 3) - (1 x 2)/(6 x 2)]

M = (8/10 - 15/10) : (-27/12 - 2/12)

M = (-7/10) : (-29/12)

M = -7/10 x (-12/29)

M = 7/29 x 12/10

M = 7/29 x (2 x 6)/(2 x 5)

M = 7/29 x 6/5

M = 42/145