Solve by factorization

8+7x-x^2=0

x = - 1, x = 8

Step-by-step explanation:

Given

8 + 7x - x² = 0 ( multiply through by - 1 and arrange into standard form )

x² - 7x - 8 = 0 ← in standard form

(x - 8)(x + 1) = 0 ← in factored form

Equate each factor to zero and solve for x

x + 1 = 0 ⇒ x = - 1

x - 8 = 0 ⇒ x = 8

$150 off

Step-by-step explanation: Four tires would cost $654. To find 20% of 654 you would have to do 654 * .20 which equals 130.8, so 20% off equals $130.80. Since $150 is greater than $130.80, $150 is the best deal