Answer:
3
Step-by-step explanation:
Let's note that the below can be considered as a significant figure;
*Any zero between non-zero digits
*Non-zero digits
*Any trailing zero when in a decimal number
So considering the given problem, if add the two numbers, we'll have;

We can see that 1530 has a trailing zero and it's not a decimal number, therefore the correct number of significant figures is 3.