Answer:
x = 5
Step-by-step explanation:
The area (A) o a rectangle is calculated as
A = lb ( l is length and b the breadth ), thus
x² + x - 12 × 
= 126 ← factor the quadratic
(x + 4)(x - 3) × = 126 ← cancel the common factor (x - 3)
(x + 4)(x + 9) = 126 ← expand factors using FOIL
x² + 13x + 36 = 126 ( subtract 126 from both sides )
x² + 13x - 90 = 0 ← in standard form
(x + 18)(x - 5) = 0 ← in factored form
Equate each factor to zero and solve for x
x + 18 = 0 ⇒ x = - 18
x - 5 = 0 ⇒ x = 5
However x > 0 ⇒ x = 5
Initial charge charged by the Singer A = $50
Hourly charge of Singer A = $20
Initial amount charged by Singer B = $100
Hourly rate charged by Singer B = $10
Let us assume the time after which both singers will charge the smae amount of money = x
Then
50 + 20x = 100 + 10x
20x -10x = 100 - 50
10x = 50
x = 50/10
= 5
So after 5 hours both Singer A and Singer B will charge the same amount of money. I hope the procedure is clear to you and you can attempt such problems in future without needing any kind of help.
The answer to your question is 20
