Answer is x-1/3x^2
Merry Christmas
So what they are saying is the sum of 2x +13=75
Therefore we can just solve for 2x, our unknown value.
2x+13=75 now subtract 13 and divide by 2 from both sides of equation to not change the equation
x+13-13=75-13
This leaves us with
x=(75-13)/2=31 therefore x=31 or our unknown value is 31.
I hope this helped. Any questions please just ask. Thank you.
We have the formula to compute the probability of having exactly k successed over n trials, given a probability p of success (and implicitly a probability 1-p of failure), which is

Now, the probability of at least 3 successes is the union of the following event: exactly three successes,exactly four successes and exactly five successes.
We can compute their probability and sum them:
So, the answer is about 36.79%
That's simple!!!
-12/19 = b/19
as denominators are same, you can cancel that.
b = -12