Answer
$-0.2x^{2}+0.2x-2.2$
Work Step by Step
$(0.7x^{2}+0.2x-0.8)-(0.9x^{2}+1.4)$
Remove both parentheses and change the sign of every term inside the second one:
$0.7x^{2}+0.2x-0.8-0.9x^{2}-1.4=...$
Simplify by combining like terms:
$...=(0.7-0.9)x^{2}+0.2x-(0.8+1.4)=-0.2x^{2}+0.2x-2.2$
