Let the age of Jacob be J
Let the age of Elizabeth be E
twice Elizabeth's age will be 2 x E = 2E
The question says Jacob is 12 years younger than twice Elizabeth's age.
This means:
Jacob is 12 years younger than 2E.
Written in equation form, we have:
Jacob's age = 2E - 12
But we know Jacob's age is represented as J. So the full form of the equation will be:
J = 2E - 12
Now if Jacob is 28, we can therefore find Elizabeth's age:
28 = 2E - 12
Add 12 to both sides
28 + 12 = 2E
2E = 40
Divide both sides by 2
E = 20
Therefore, Elizabeth's age is 20