Question 626316
Given:
 x = Tom's age
 y = sister's age

Tom Johnson is 1 year less than twice as old as his sister.
 x = 2y - 1  ==> equation 1

The sum of their ages is 14
 x + y = 14  ==> equation 2

Find:
  Tom's age which is represented by x

Solution:
  From equation 1; x = 2y - 1

  Substitute the value of x from equation 1 to equation 2
  x + y = 14
 (2y - 1) + y = 14
 3y - 1 = 14
 3y = 14 + 1
 3y = 15
divide both sides by 3 giving us:
  y = 5

therefore the age of tom's sister is 5yrs old

To compute for Tom's age. Use any of the two equations given.
from equation 2:

  x + y = 14
 substitute y ( sister's age) to the equation
  x + 5 = 14
  x = 14 - 5
  x = 9

Therefore Tom's age is 9 yrs old

Checking:

Use any of the equation 1 or 2 for checking.
Use equation 1:
  x = 2y -1
substitute the value of x and y
  9 = 2(5) - 1
  9 = 10 - 1
  9 = 9 ====>checked!