Answer
$34-13i$
Work Step by Step
Step 1: $(3+4i)(2-7i)$
Step 2: $3(2-7i)+4i(2-7i)$
Step 3: $3(2)+3(-7i)+4i(2)+4i(-7i)$
Step 4: $6-21i+8i-28i^{2}$
Step 5: Since $i^{2}=-1$, the expression becomes
$6-21i+8i-28(-1)$
Step 6: $6-21i+8i+28$
Step 7: $6+28-21i+8i$
Step 8: $34-13i$