Answer:
The longest side is 16 cm
Step-by-step explanation:
[tex]x + (x + 2) + (x + 4) = 42cm \\ x + x + 2 + x + 4 = 42cm \\ 3x + 6 = 42cm \\ 3x = 36cm \\ x = 12[/tex]
check and finish
[tex]12 + (12 + 2) + (12 + 4) = 42cm \\ 12 + 12 + 12 + 6 = 42 cm\\ 36 + 6 = 42cm \\ 42cm = 42cm[/tex]
lengths of sides
[tex]12 + 4 = 16cm \\ 12 + 2 = 14cm \\ 12cm[/tex]