Substitute the numbers in x and solve.
1) 4/5^x
-2,-1,0,1,2
2) 2^x
-2,-1,0,1,2
plug and chug:
f(x) = 4/5^x
f(-1) = 4/5^-1 = 4/(1/5) = 4*5 = 20
f(0) = 4/5^0 = 4/1 = 4
f(1) = 4/5^1 = 4/5
f(x) = 2^x
f(-1) = 2^-1 = 1/2
f(1) = 2^1 = 2
If you have troubles with the other values, come on back and show where you get stuck.