Since ∠ABC is a right angle, we shall use Pythagoras Theorem to solve for x.
[tex]\boxed {\boxed{a^2 + b^2 = c^2}}[/tex]
[tex]x^2 + 7^2 = ( x + 5)^2[/tex]
[tex]x^2 + 49 = x^2 + 10x + 25[/tex]
[tex]10x = 49 - 25[/tex]
[tex]10x = 24[/tex]
[tex]x = 2.4[/tex]
Answer: x = 2.4
