1) 60:4 •3 =45 (мин)
2) 40 • 45 + (40+5) • 45 = 3825 (б.) - за 45 мин
3) 5780 ÷ (40+45) = 68 ( мин )
№6 =6!/(6-2)!=1*2*3*4*5*6/1*2*3*4=30
1) 105/200 = 21/40 = 0,525
2) 405/900 = 45/100 = 9/20 = 0,45
3) 705/800 = 141/160 = 0,88125
4) 140/210 = 20/30 = 2/3