Direct method:
sister ---- x
Monica --- (1/3)x or x/3
6 years from now:
age of sister = x+6
Monica's age = x/3 + 6
x/3 + 6 = (1/2)(x+6)
multiply each term by 6, the LCD
2x + 36 = 3(x+6)
2x+36 = 3x + 18
18 = x
The sister is 18, and Monica is 6
or
sometimes fractions can be avoided by rephrasing the conditions:
if Monica is 1/3 her sister's age, then the sister is 3 times as old as Monica
let Monica's age be y
then sister's age is 3y
in 6 years, Monica will be y+6 and the sister 3y+6
At that time, Monica is half as old as the sister,
or
the sister is twice as old as Monica
3y+6 = 2(y+6)
3y + 6 = 2y+12
y = 6 , ---> 3y = 18
So Monica is 6, the sister is 18
Monica is one-third as olf as her sister. six years hence she will be one-half as old as her sister find their present age
2 answers
Monica is one-third as old as her sister. Six years hence, she will be one-half as old as her sister. Find the present age of monica