Respuesta :

valex20

[tex]lowest = x \\ highest = x + 42[/tex]
[tex]2x + 42 = 138[/tex]
[tex]138 - 42[/tex]
[tex]2x = 96[/tex]
[tex]2x \div 2x \\ 96 \div 2[/tex]
[tex]x = 48[/tex]
[tex]48 + 42 = 90[/tex]
the lowest grade is 48, while the highest is 90.