Add: $20 x^{2} y^{2} z and -10 x^{2} y^{2} z$

Solution:

Add 20 x^2 y^2 z and − 10 x^2 y^2 z means

$20 x^{2} y^{2} z + (− 10 x^{2} y^{2} z)$

= $20 x^{2} y^{2 }z − 10 x^{2} y^{2} z$

= $10 x^{2} y^{2} z$ as they are like terms

So $20 x^{2} y^{2} z + (− 10 x^{2} y^{2} z) = 10 x^{2} y^{2} $z