Use the appropriate significant figure in calculating the following:

a$.$ the total weight of a $10kg$ sample and a $10-$pound object

b$.$ the weight in $1l{b}_f$ of a $25\mathrm{.}0-l{b}_m$ object

c$.$ the mass in $kg$ of an object that weighs $25$ newtons

d$.$ the weight in dynes of a $10.-$ton object $($not metric tons$)$

e$.$ A large tank weighs $1510N$; a fitting of $3\mathrm{.}55N$ is added to the tank. What is the total weight of the system?