When you find the upper and lower bounds of values with decimals, you will decrease or increase the value by increments of 0.05. Since we are just trying to find the upper bound we will add 0.05 to the values we are given.
15.6 + 0.05 = 15.65cm
3.8 + 0.05 = 3.85cm
Now that we have those values, we can find the perimeter using the formula [ 2(L + W) ]