A decagram is 10 grams, so first lets convert the decagrams to grams and then after we'll change to kilograms.
If 1 decagram equals 10 grams, then 2500 decagrams is equal to:
2500*10 = 25000 grams
Now, 1 kilogram equals 1000 grams so 25000 grams equals:
25000/1000 = 25 kg
therefore, 2500 decagrams equals 25 kg
4,320 because if you take 720 and multiply it by 6 you get your answer
the answer for 1296.5 times 10.2 is
13224.3
Do 12-5 then 6.4 then 2.2 then whatever answer you get for 12-5 multiply it by the answer you get for 6.4 then subtract whatever answer you get for 2.2 hope this helps!