Ella started to solve the proportion x+16=2x−3 by using cross products.

She continued correctly solving the problem until she got stuck. Analyze Ella's work below.

6(2)120=(x+1)(x−3)=x2−2x−3=x2−2x−15

Which step should be taken next and why?

Ella should isolate the constant because she can then factor the remaining terms and use the Zero Product Property to solve for x.
Ella should isolate the x2 term because she can then take the square root of both sides of the equation to solve for x.
Ella isolate the x term because she can then simplify the remaining expression to solve for x.
Ella should use quadratic formula to find the solutions since the expression is not factorable over the integers.
Ella should factor the expression to find the roots because she can then use the Zero Product Property to solve for x.