Răspuns:
3×(7+10-5)= 3×7+3×10-3×5=21+30-15=36
3×(7+10-5)=3×12=36
3 × ( 7 + 10 - 5 ) =
3 × ( 17 - 5 ) =
3 × 12 = 36
al 2 lea mod :
3 × 7 + 3 × 10 - 3 × 5 =
21 + 30 - 15 =
51 - 15 = 36