now i am stuck again...i feel I should know this stuff..the problem is

243.5-87.1289=1.2/1.753-0.0473-5.4

express the result wityh the crrect number of significant figures..breaking it down I came up with 157.57/-3.69...well I know thts not right...the answer is-4.3x10to the 1 how did they get that *delete me*!!!!!!!!!!