Answer: Jack is 8 years old (option A)
Step-by-step explanation:
Hi, to answer this question we have to write an equation using the information given:
Twice : Means that the age of jack (j) is multiplied by 2 (2j),
Plus 5: we have to add 5 (2j+5).
Is 21: all is equal to 21.
Mathematically speaking:
2j +5 =21
Solving:
2j =21-5
2j =16
j= 16/2
j=8
Option A). 8
Feel free to ask for more if needed or if you did not understand something.
