I am going to assume that x2 = x squared
So: X^2 + 3x -40
= (X+8)(X-5)=0
X+8 = 0
X= - 8
The other solution is X -5 = 0
X = 5
Therefore the solution set is {-8, 5}
You can just use the tn formula to solve this tn= t1 + (n-1)d
positive number times negative number is negative number "(+)(-) = (-)".

we change the mixed numbers to the improper fractions

It's A. If an instrument is a piano, then it has keys.