Answer:
12.9g+2.3k
Explanation:
perimeter=add all sides
you can only add numbers that have the same variable (if there is one)
so you would do 5.7k-3.4k=2.3k, and then you would do 10.5g+2.4g=12.9g
and since you can't combine 2.3k and 12.9g (since they don't have the same variable) you leave it as it is '12.9g+2.3k'