Răspuns :

Răspuns:

M+m=27

M=27-m

7,60×M+2,40×m=142,80

7,60M+2,40m=142,80

7,60(27-m)+2,40m=142,80

205,2-7,60m+2,40m=142,80

205,2-142,80=7,60m-2,40m

62,4=5,20m

m=12 (timbre mici)

M=27-m

M=15 (timbre mari)

Explicație pas cu pas: