Răspuns:
Explicație pas cu pas:
a)x+3•a-3•b=20
x + 3*(a - b) = 20
x + 3*6 = 20
x + 18 = 20
x = 20 - 18 = 2
b)x•a-x•b+9a-9b=654
x*(a - b) + 9*(a - b) = 654
(a - b)*(x + 9) = 654
6*(x + 9) = 654
x + 9 = 654 : 6 = 109
x = 109 - 9 = 100
c)7•a-7•b+x=55
7*(a - b) + x = 55
7*6 + x = 55
42 + x = 55
x = 55 - 42 = 13
d)13+x-(5•a-5•b)=2011
13 + x - 5*(a - b) = 2011
13 + x - 5*6 = 2011
13 + x - 30 = 2011
x = 2011 + 30 - 13 = 2028
