aide pour ex 14 et 15 merçi

14)
K = 21-8x4
L = 21x(8-4)
M = 21-(8-4)
R = 21x8-4
S = (21+8-1)/4
T = 21-[8-4x2]

15
A = 5x2 +3,7
B = 4x(9,2+7)
C = 17-4x3
D = (1,9+3,11)/11
E = 7x9 + (12-4)