1 pound is 0.453592 kilograms
so 8.4 pounds is 3.81018 kilograms
You would cross multiply and make sure the units are lined up with each other
1

then you would cross multiply and get 3.81018
subtract 3 from 23 and u will get 20 then divide 2 by 2 and 2 by 20
x= 10
3/6 = x/7
Multiply x and 6, 3 and 7:
6x = 7*3
x = 21/6
x = 7/2
Don't know what the question is asking but the are for the skate park would be 3000