SOLUTION: Mike is twice as old as his sister. Together, their ages add up to 30. How old are Mike and his sister?

Question 1015951: Mike is twice as old as his sister. Together, their ages add up to 30. How old are Mike and his sister?
Found 2 solutions by fractalier, Herdaysoji:
Answer by fractalier(6550) (Show Source): You can put this solution on YOUR website!
Call Mike's and his sister age, m and s. Then we have
m = 2s and
m + s = 30
Substitute the first equation into the second and get
2s + s = 30
3s = 30
s = 10 and then
m = 20
Answer by Herdaysoji(25) (Show Source): You can put this solution on YOUR website!
Let mike be x and sister be y
mike is twice his sister age
.'.x=2y
sum of thier age is 30
.'. x+y=30
since x=2y
.'.2y+y=30
3y=30
y=30/3
y=10 and x= 20
RELATED QUESTIONS
Mike is twice as old as his sister. Together their ages add up to 30. How old are Mike... (answered by Alan3354)
jack is twice as old as his sister tia together their ages add up to 21 how old are the... (answered by pmesler)
Mike is two years younger than his sister Sarah. If in 3 years their ages add up to 48,... (answered by Cromlix)
John is 4 years older than his sister Mary. Together, their ages add up to 30. How old is (answered by ikleyn)
A man is twice as old as his son. Together, their ages add up to 63. How old are the man... (answered by Alan3354)
Mike is now 5 years old. His older sister, Kim is three times as old as Mike. When Mike... (answered by tommyt3rd)
Pedro is three less than twice as old as his sister Sofia . John is four times as old as... (answered by greenestamps)
Pedro is five less than three times as old as his sister Sofia. John is twice as old as... (answered by mananth,josgarithmetic)
mike is 2 years older than his sister tia. twelve years ago he was twice as old as she... (answered by mike69)