ANSWER
[tex]3)19[/tex]EXPLANATION
Let Jody's age be j.
Let Jody's brother's age be b.
His brother is three years less than twice his age. This means that:
[tex]b=2j-3[/tex]The sum of their ages is 30. This means that:
[tex]b+j=30_{}[/tex]We now have two simultaneous equations:
[tex]\begin{gathered} b=2j-3 \\ b+j=30 \end{gathered}[/tex]Substitute the first equation into the second equation:
[tex]\begin{gathered} 2j-3+j=30 \\ 3j=30+3=33 \\ j=\frac{33}{3} \\ j=11 \end{gathered}[/tex]To find b, substitute the value of j into the first equation:
[tex]\begin{gathered} b=2(11)-3=22-3 \\ b=19 \end{gathered}[/tex]That is the age of Jody's brother.
