Пошаговое объяснение:
90-18=9с
72=9с
с=72÷9
с=8
Ответ:
19/45
0,1
25/90
3/5–1/8 = 24/45–5/45= 19/45
54/60–32/40=108/120–96/120= 12/120=1/10=0,1
13/30–(2/45+1/9)= 13/30– (2/45+5/45) = 13/30–7/45= 39/90–14/90= 25/90