determine if each expression is equivalent to -2.7 + (-4.9)
a -2.7 - 4.9
b -2.7 + (-0.4 - 4.5)
c -2.7 + 0.4 - 4.5
d -2.7 + (-0.7 + (4.2)
e -2.7 - 0.7 + 4.2