a = 5/36 + 1/24
36 = 2²×3²
24 = 2³×3
cmmmc al numerelor (36, 24) = 2³×3²=72
a = (2×5) /72 + (3×1) / 72 = 10/72 + 3/72 = 13/72
b=5/48 + 1/36 =
48 = 4²×3
36 = 4×3²
cmmmc al numerelor ( 48, 36 ) = 4²×3²= 144
b = 15/144 + 4/144= 19 / 144
a+b = 13/72 + 19 /144 =(2×13) / 144 + 19/144 = (26 + 19) / 144 = 45/144=
= ( 45 : 9) / ( 144 : 9) = 5/16 = 0,3125
