## Basic College Mathematics (9th Edition)

$\frac{-3s - t - 4 }{-s - 20 - t }$ Replace s= -3, t = -6 $\frac{-3(-3) - (-6) - 4 }{-(-3) - 20 - (-6)}$ Do all the Multiplications first $\frac{9 +6 - 4 }{3 - 20 +6}$ Addition and subtraction from left to right in numerator and denominator $\frac{15 -4}{-17 +6}$ =$\frac{11}{-11}$ Dividing two numbers with opposite sign gives the negative result. =-1