The probability that 4 are chem majors would be 5%
In the second fraction, factorize the denominator:
Then we have, as long as ,
which you could also write as
Hey!
so first distribute the 5 to x + 4
5x+20 = 2x + 20 + 2x
combine 2x and 2x
5x+20 = 4x + 20
Now you want the constant and variable on different sides so subtract 4x to the other side
5x - 4x + 20 = 20
1x + 20 = 20
now subtract the 20 on the 1x + 20 side to the other side
1x = 0
divide by 1
0 divided by anything is 0
So x = 0
Hope this helps!