Explanation:
Let the price of CD, tshirt and jeans be x,y and z respectively.
given:
x+2y+2z=133......(i)
y=x+13.......(ii)
2z=y+30....(iii)
in eqn (iii) ,
2z=y+30
or, 2z=x+13+30
or, z=(x+43)/2....(iv)
now in eqn (i),
x+2y+2z=133
or, x+2(x+13)+2((x+43)/2) =133
or, x+2x+26+x+43=133
or, 4x=133-69
or, x= 64/4
•°• x=$16