Let m and j be the current ages of Matthew and Jenny, respectively.
Now, Matthew is 3 times as old as Jenny, so the variables are in the following relation:

In 7 years, both of them will be 7 years older, i.e. their ages will be m+7 and j+7, and Matthew will be twice as old:

Now, remembering that m=3j, we can rewrite the second equation as

So, Jenny is 7 and Matthew is 21 (he's 3 times older).
In fact, in 7 years, they will be 14 and 28, and Matthew will be twice as old.
Hello!
x² - 4x + 6 = 9 <=>
<=> x² - 4x + 6 - 9 = 0 <=>
<=> x² - 4x - 3 = 0 <=>
<=> x = -(-4)±√(-4)²-4×1×(-3)/2×1 <=>
<=> x = 4±√16+12/2 <=>
<=> x = 4±√28/2 <=>
<=> x = 4±2√7/2 =>
=> x = 4+2√7/2 and x = 4-2√7/2 =>
=> x = 2+√7 and x = 2-√7
The equation has two solutions.
Good luck! :)
Answer:
You would have to add the expression so we know what you're talking about.
Any multiple of those numbers is equivalent though.
Step-by-step explanation: