hello
to solve this qestion, we just need to evaluate this expression
1. 2000 + 20.5
the answer is 4 signifigant figures. it can be further rounded up to make 2021 which is a four significant figure
2. 45
the number 45 is a two significant figure
3. 6.01
this can be rounded down into 6.0 which is in 1 significant figure
4. 106.2 + 54.07
the answer value is 160.27 which is a three significant value.