let the first number is a
the second number is b
so, it is given One-third of a number decreased by the second number equals 11,
[tex]\frac{a}{3}-b=11[/tex]also, One-third of the first number increased by the second number is equal to 1.
[tex]\frac{a}{3}+b=1[/tex]add both the equation
[tex]\begin{gathered} 2\times\frac{a}{3}=12 \\ a=18 \end{gathered}[/tex]so the first number is a = 18
put a = 18 in the first equation
[tex]\frac{18}{3}-b=12[/tex][tex]\begin{gathered} 6-b=12 \\ b=6-12 \\ b=-6 \end{gathered}[/tex]so the second number is -6
so the numbers are 18 & -6
