A moving van crew picks up the following items: a sofa that weighs 158 pounds, a chair that weighs 65.7 pounds, a piano that weighs 3.8*10^2 pounds, and several boxes with a combined weight of 147.65 pounds. What total weight in pounds should be listed on the billing sheet? Express your answer in scientific notation.

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.