Please hurry will mark brainiest

Step-by-step explanation:

x(x+8) = 450

x² + 8x - 450 = 0

Quadratic formula:

x = [-8±√(8²-4(1)(-450))]/[2(1)]

= [-8±2√466]/2

= -4±√466

≅ 17.59, -25.59

-25.59 is an extraneous solution, so x ≅ 17.6 inches.

The dimensions of the blackboard are 17.59 inches by 25.59 inches  

6,250

step-by-step explanation:

to get the area, multiply 360 by 160.(57,600)

to find out how many bags of fertilizer it will take, first figure out how many square feet one bag can hold. divide 1000 by 8(125) to get the unit rate(how many square feet one pound of fertilizer can hold)and multiply it by 50(6250). if i haven't made a mistake, that is the answer.