Zack used these steps to solve this equation: Three-fourths y + 5 = negative three-fourths y minus 9. Step 1: StartFraction 6 Over 4 EndFraction y + 5 = negative 9. Step 2: StartFraction 6 Over 4 EndFraction y = negative 14. Step 3: (StartFraction 6 Over 4 EndFraction) StartFraction 6 Over 4 EndFraction y = negative 14 (StartFraction 6 Over 4 EndFraction). Step 4: y = negative 21. When Zack checked his solution, it didn’t work. What was his mistake? In step 1, he should have used the multiplication property of equality. In step 2, he should have a constant of – 4 on the right side. In step 3, he should have divided both sides by StartFraction 6 Over 4 Endfraction. In step 4, the answer should be positive.

C.In step 3, he should have divided both sides by 6/4.

Step-by-step explanation:

I just took the assignment

(b) 240

step-by-step explanation:

first, we use the pythagorean formula using the given side lengths to find x. then we use x to find the side lengths. then we add the side lengths to find the perimeter.

pythagorean theorem formula:

a^2 + b^2 = c^2

(x - 20)^2 + (x - 40)^2 = x^2

x^2 - 40x + 400 + x^2 - 80x + 1600 = x^2

x^2 -120x + 2000 = 0

(x - 100)(x - 20) = 0

x - 100 = 0 or x - 20 = 0

x = 100 or x = 20

we see that the solution x = 20 must be discarded because it will give a negative side length and a side length of 0. the only valid solution is x = 100.

perimeter = sum of the lengths of the sides

perimeter = x + x - 20 + x - 40

perimeter = 3x - 60

replace x with 100.

perimeter = 3(100) - 60

perimeter = 300 - 60

perimeter = 240