Okay so for activity 1 remember PEMDAS (parentheses, exponents, multiply and divide left to right, add and subtract left to right) so work shown should look like this
60-20+30+50-40=
40+30+50-40=
120-40= 80
100-25+10-35=
75+10-35=
85-35= 50
Activity 2 for the perimeter you add both lengths and both widths so
20+20+10+10=60 units
For the area of the rectangle it is length multiplied by the width so 10x6=60 square units