Don is 21 years older than Betty. In six year Don will be twice as old as Betty. How old is each now?
If b is betty's age, then Don is b+21
In 5 years their ages will be b+6 and b+27
So,
b+27 = 2(b+6)
Solve for b, then you can get Don's age.
To solve this problem, let's denote Betty's current age as "B" and Don's current age as "D."
According to the problem, Don is 21 years older than Betty. This can be expressed as:
D = B + 21
In six years, Don will be twice as old as Betty. Therefore, we can also express this as:
( D + 6 ) = 2 * ( B + 6 )
To find the current ages of Don and Betty, we can set these two equations equal to each other and solve for D and B.
I. D = B + 21
II. ( D + 6 ) = 2 * ( B + 6 )
Let's solve this system of equations.
First, substitute the value of D from equation I into equation II:
( B + 21 + 6 ) = 2 * ( B + 6 )
B + 27 = 2B + 12
Next, simplify the equation by subtracting B from both sides:
27 = B + 12
Subtract 12 from both sides:
15 = B
Therefore, Betty's current age is 15.
Now, substitute the value of B into equation I to find Don's current age:
D = B + 21
D = 15 + 21
D = 36
Therefore, Don's current age is 36, and Betty's current age is 15.
Betty is X years old.
Don is X+21 years old.
Six years from now:
Betty: X+6 years old.
Don: (X+21) + 6.
(X+21)+6 = 2(x+6).
X = ?
x+21 = ?
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