What is (2+5i) + (7-3i)?

Add the real parts and the imaginary parts separately: $(2+7)+(5-3)i=9+2i$, choice F. Choice H ($9-2i$) loses the sign of the imaginary part by computing $-5-3$ or $-3-5$ instead of $5+(-3)$. Choice G ($5+8i$) subtracts the second number from the first, $(7-2)+(5-(-3))i$, which is subtraction, not addition, and mixes the order of the terms. Choice J ($14-15i$) multiplies the parts instead of adding them. Adding complex numbers works like combining like terms, with $i$ treated as a variable.