My answers wrong - simplify by combining like terms

19) you have to look for similar terms

you can see there is more than one term with y^2 in it

-3y^2 - 5y^2

= -8y^2

there is also more than one 'z' term

3z-5z = -2z

dont forget about the 4x^2 and put it together

answer = 4x^2 - 8y^2 - 2z

i think you got confused because of the way you laid out your working??

next time identify the like terms and try working them out seperately first