[tex]7)20 \frac{1}{4} = \frac{20*4+1}{4} = \frac{81}{4} mere \\ \\ 10 \frac{1}{5} = \frac{10*5+1}{5} = \frac{51}{5} pere \\ \\ 25 \frac{3}{5} = \frac{25*5+1}{5} = \frac{128}{5} prune \\ \\ \frac{81}{4} + \frac{51}{5}+ \frac{128}{5} = \frac{5*81+4*51+4*128}{4*5} = \frac{2670464}{20} [/tex]
8) 25(1/2)=(25*2+1)/2=(50+1)/2 ; in prima zi a parcurs 51/2
40(1/3)=(40*3+1)/3=121/3; a doua zi 121/3
100-51/2-121/3=205/6 .205/6 ..cat a parcurs in ziua 3
se aduce la acelasi numitor comun (6)
(6*100-3*51-3*121)/6=(600-153-242)/6=205/6.
...proba adunam
51/2+121/3+205/6=(51*3+121*2+205)/6=(153+242+205)/6=600/6=100 km
7)
7)20(1/4)
= (20*4+1)/4 = 81/4 mere
10(1/5)=(10*5+1)/5
= 51/5 pere
25(3/5)=(25*5+1)/5=128/5
prune
81/4+51/5+128/5=(5*81+4*51+4*128)/4*5=
2670464/20
