Răspuns:
a) x=2; b) x=100; c) x=13; d) x=2028.
Explicație pas cu pas:
a-b=6 a) x+3•a-3•b=20=×+(3•6)=20=×+18=20
x=20-18 ×=2
b)וa-וb+9a-9b=654=ו6+9a-9b=654=ו6+9•6=654=ו6+54=654 ו6=654-54 ו6=600 ×=600÷6 ×=100
c) 7•a-7•b+×=55 7•6+×=55 42+×=55 ×=55-42 ×=13
d) 13+×- (5•a-5•b)=2011 13+×-5•6=2011 13+×-30=2011 13+×=2011+30 13+×=2041 ×=2041-13 ×=2028
Sper că te-am ajutat!:)