<span>1)</span>
<span>а)3/4*1/5 = (3*1).(4*5)=3/20 = 15/100 = 0,15</span>
<span>б)2/3 * 1целая1/3 =2/3 * 4/3 = (2*4)/(3*3)=8/9</span>
<span>в)3/4+1/1 = 3/4+4/4 = (3+4)/4 =7/4=1,75</span>
<span>г)1 целых -5/6:8/9 = 1-5/6*9/8=1-5*9/(6*8) = 1-5*3/(2*8)=1-15/16=1/16</span>
<span>2) </span>
<span><span> 2 целых-4 целых умножить (1 целая 1/6-2/3):1 целая 3/5 =</span></span>
<span><span>= 2 - 4*(1+1/6-2/3)/(1+3/5) = 2 - 4*((6+1-4)/6)/((5+3)/5) = 2 - 4*(3/6)/(8/5) = 2 - (4*3/6)*(5/8) =</span></span>
<span><span> = 2 - (4*1/2)*(5/8) = 2 - 2*5/8 = 2 - 1*5/4 = 2 - 5/4 = (8 - 5)/4 = 3/4</span></span>
1)61*3=183км -на 1 участке 2)86*2=172км -на 2 участке 3)183+172=355км-всего проехал 4)355/(3+2)=71км/ч
7/10+7/15=21/30+14/30=35/30=7/6=1 1/6
4/9+1/6=8/18+3/18=21/18=7/6=1 1/6