3/4x + ax=10 in the equation above, a is a constant. if x=24 is the solution to the equation, what is the value of a

[tex]\\ \sf\longmapsto \dfrac{3}{4}x+ax=10[/tex]
[tex]\\ \sf\longmapsto \dfrac{3}{4}(24)+24a=10[/tex]
[tex]\\ \sf\longmapsto 3(6)+24a=10[/tex]
[tex]\\ \sf\longmapsto 18+24a=10[/tex]
[tex]\\ \sf\longmapsto 9+12a=5[/tex]
[tex]\\ \sf\longmapsto 12a=5-9=-4[/tex]
[tex]\\ \sf\longmapsto 3a=-1[/tex]
[tex]\\ \sf\longmapsto a=\dfrac{-1}{3}[/tex]