I’m sorry if I’m wrong but the equation be 3x+6=2x and if you solve that, x=6.
Explanation: 3x+6=2x
-3x. -3x
6=x
X^2-5x, given x=7,
(7)^2-5(7)=14
sqrt(14)=3.74
The probability of one dice rolling an even number is 1/2 as half the numbers are even. Since the events are independent, and there are 2 dice, we need to square 1/2 to get 1/4, assuming they are both fair dice