Let 'x' represent the boxes of apples.
Let 'y' represent the boxes of pears.
The cost of 4 boxes of apples and 5 boxes of pears is $20.
The mathematical expression is,
[tex]4x+5y=20.........1[/tex]The cost of 6 boxes of apples and 3 boxes of pears is $21.
The mathematical expression is,
[tex]6x+3y=21...........2[/tex]Combining the two equations together
[tex]\begin{gathered} 4x+5y=20..............1 \\ 6x+3y=21.............2 \end{gathered}[/tex]Using Substitution method ofsimulataneous equqation to find