2. Evaluate each expression when a = 4 and b = -1.
a) a + b - 3
b) -2a - 3b + 7
c) 3b - 5 + a
d) 1 + 2a - 3b
e) [tex] \frac{3}{4} [/tex]a + b
f) b - [tex] \frac{1}{2} [/tex]a