Given

2x + 5 = 23 – x

2x + x = 23 – 5

3x = 18

On simplifying

x = 18/3

We get,

x = 6

Verification

LHS = 2x + 5

= 2(6) + 5

= 12 + 5

= 17

RHS = 23 – x

= 23 – 6

= 17