#### Answer

$3x^{2a}+2x^{a}+.7$

#### Work Step by Step

We are given $(4x^{2a}-3x^{a}+.5)-(x^{2a}-5x^{a}-.2)$. We can subtract the second polynomial from the first polynomial by adding the opposite of the second polynomial to the first polynomial.
$(4x^{2a}-3x^{a}+.5)+(-x^{2a}+5x^{a}+.2)$
Next, we can combine like terms.
$(4x^{2a}-x^{2a})+(-3x^{a}+5x^{a})+(.5+.2)=3x^{2a}+2x^{a}+.7$