Five years ago, John’s age was half of the age he will be in 8 years. How old is he now? Show your steps.

 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.

0.02

step-by-step explanation:

time of 9 192 631 770 periods of the radiation corresponding to the transition between the 2 hyperfine levels of the ground state of the caesium 133 atom at 0 k (but other seconds are sometimes used in astronomy)