Respuesta :

Answer:  John is 18 now

Step-by-step explanation:

If his age 5 years ago was half of his age 8 years from now, the equation can show that doubling that age will be equal to his current age plus  8 years.

2(x-5) = x + 8 .  diistribute

2x - 10 = x + 8  Subtract x from both sides 2x -x +10 = x-x +8

x -10 = 8 . Add 10 to both sides . x -10 +10 = 8 + 10  simplify.

x = 18

Check:

18-5=13,  18+8= 26 .  13 is half of 26. True.