Answer:
1: 3\sqrt2 - \sqrt14
2: \sqrt21 - 2\sqrt(7)
3: 4\sqrt3 - \sqrt15
4: 2\sqrt5 - \sqrt10
5: -3 + 3\sqrt5
I already gave you these answers man
Step-by-step explanation:
If we know that 30% of the time is used after 9 minutes we can write this mathematically as:

By solving for x we can determine the total time allowed to play games and so:

The total time allowed to play games is 30 minutes. Since 9 minutes have lapsed 30-9=21 minutes left to play.
Answer: $6
Step-by-step explanation:
x = 13
subtract x from both sides of the equation
6 = 2x - x - 7
6 = x - 7
add 7 to both sides
6 + 7 = x ⇒ x = 13
As a check
substitute this value into the equation and if both sides are equal then it is the solution
left side = 13 + 6 = 19
right side = (2 × 13) - 7 = 26 - 7 = 19
hence x = 13 is the solution