Answer
$-\dfrac{1}{10}$
Work Step by Step
Make the fractions similar using their LCD, which is 10, to obtain:
$=\dfrac{7}{10} + \left(-\dfrac{8}{10}\right)$
The addends have opposite signs, so subtract the smaller absolute value from the bigger absolute value, andthen use the sign of the number with the bigger absolute value to obtain:
$=-(\frac{8}{10} - \frac{7}{10}) \\\\ -(\frac{1}{10})
\\=-\frac{1}{10}$
