3. 6abcde=abcde6*4
e=4 (6*4=24)
6abcd4=abcd46*4
d=8 (4*4+2=18)
6abc84=abc846*4
c=3 (4*8+1=33)
6ab384=ab3846*4
b=5(4*3+3=15)
6a5384=a53846*4
a=1 (4*5+1=21)
615384=153846*4
6+1+5+3+8+4=27
suma este 27
1. 3(1+2+...+abc:3)=abc*100
notez abc:3=x
3x(x+1):2=100*3x
impart prin 3x
(x+1):2=100
x+1=200
x=199
abc=3*199=597
abc (cu bara deasupra)=597
a+b-c=7