840 ways for the children to sit.
First of all, x cannot ever equal -1 because if it does then in the original equation you'd be dividing by 0, which is not possible. anything divided by 0 is undefined.
I think the error was in the second step: x(x+1) = 2(x+1) because they didn't need to go from the first step to there. I'm assuming they multiplied both sides of the equation with (x+1) to get rid of the fraction, but since both sides have (x+1) as the denominator the (x+1) would've cancelled out instead of multiplying with the numerator.
Correction:

as u can see, in the second step of this correction, the (x+1)s on both sides cancel out so only the numerators remain.
Hope this helps!
Answer:
sorry but i cant answer that quiestion
Answer :Anita's age = 7 years
Basilio's age = 2.5 years
Step 1. Assign variables to Anita's and Basilio's ages.
Anita's age = A
Basilio's age = B
Step 2. Use the information given to form two equations.
Anita is 4-1/2 years older than Basilio
A = 4.5 + B
Three times Anita's age added to six times Basilio's age is 36
3A + 6B = 36
Step 3. Substitute the value of A from first equation in to the second equation and solve for B
3(4.5 + B) + 6B = 36
13.5 + 3B + 6B = 36
13.5 + 9B = 36
9B = 36 - 13.5
9B = 22.5
B = 22.5/9 = 2.5
Step 4. Find the value of A
A = 4.5 + 2.5 = 7
Answer:
Anita's age = 7 years
Basilio's age = 2.5 years