Răspuns:
Explicație pas cu pas:
probl 19.
a+b=262;
a=262-b;
a-38=1/3*b;
262-b-38=b/3;
786-3b-114=b;
-4b=114-786;
-4b=-672;
b=168;
a=262-168;
a=94;
probl 20.
a+m=1176;
a=1776-m;
a-325=m-128;
1776-m-325=m-128;
-m-m=-128+325-1776;
-2m=-1579;
m=789.5;
a=1776-789.5;
a=986.5;
probl 18
a+b+c+d=cele 4 nr consecutive impare;
a+b+c+d/9=68+4;
a+b+c+d=9*68+4;
a+b+c+d=612+4;
a+b+c+d=616;
616/4=154;
cifrele sunt 151,153,155,157;
adunate cifrele dau 616;
probl 17.
a+b+c=375;
2a=b+c;
a=b+c/2;
b=c+120;
b+c/2+c+120+c=375;
c+120+c/2+c+120+c=375;
c+120+c+2c+240+2c=750;
6c=750-240-120;
6c=390;
c=65;
b=65+120;
b=185;
a=185+65/2;
a=125;
probl 16;
c+m+p=86;
c=2m+8;
p=(c+m)-38;
2m+8+m+c+m-38=86;
4m+c=86+38-8;
4m+c=86+30;
4m+c=116;
c=2m+8;
4m+2m+8=116;
6m=116-8;
6m=108;
m=108/6;
m=18;
c=2*18+8;
c=44;
p=c+m-38;
p=44+18-38;p=24;
