Answer:
[tex]\mathsf{x = \frac{31}{3}}[/tex]
Step-by-step explanation:
[tex]\textsf {Given :}[/tex]
[tex]\implies \mathsf {x + 26 = y}[/tex]
[tex]\implies \mathsf {y - 12 = z}[/tex]
[tex]\implies \mathsf{x + y + z = 71}[/tex]
[tex]\textsf {Substitute for y and z in the 3rd equation :}[/tex]
[tex]\implies \mathsf {x + x + 26 + y - 12 = 71}[/tex]
[tex]\implies \mathsf {2x + 14 + x + 26 = 71}[/tex]
[tex]\implies \mathsf {3x + 40 = 71}[/tex]
[tex]\implies \mathsf {3x = 31}[/tex]
[tex]\implies \mathsf {x = \frac{31}{3}}[/tex]