Upper and Lower Bounds - Adding and Multiplying

If a = 32 and c = 19 have been rounded to the integer find the lower bound of a + c

If j = 52 and e = 32 have been rounded to 2 significant figures find the lower bound of j + e.

If q = 500 and x = 300 have been rounded to the nearest hundred find the lower bound of q + x.

If u = 22.4 and z = 86.5 have been rounded to 3 significant figures find the upper bound of u + z.

If a = 9300 and k = 5200 have been rounded to 2 significant figures find the lower bound of a + k.