Question

Помогите плиз
номер 503 под а) и б)

Answer 1

(1/6 +2/3)*3 = ( 1/6+4/6)*3 = 5/6*3 = 5*3/6*1= 5/2= 2 1/2 = 2,5

(17/30 -2/15): 13 = (17/30- 4/30):13= 13/30 :13= 13*1/30*13= 1/30