Jane and Jill were simplifying the expression (2x² + x) + 21-x² + x) and obtained different answers. Who is

correct and why?

2x2+x+21−x2+x

=2x2+x+21+−x2+x

=2x2+x+21+−x2+x

=(2x^2+−x^2)+(x+x)+(21)

=x^2+2x+21

step-by-step explanation:

given perimeter: 28cm

length: 9cm

atp,

2(l+w)=p of the reactangle

2(9+x)=28

18+2x=28

2x=28-18

x=10/2

x=5

therefore width is 5 cm