Answer:
5+6)+(4+7)+3
11+11)+3
22+3
25
9514 1404 393
5 +(6 +4) +(7 +3)
Step-by-step explanation:
"Regroup" in this context means relocate pairs of parentheses any way you like. There are many different correct answers.
Here, pairs of terms are grouped. You can group more, or different pairs. Some possibilities are ...
(5 +6) +((4 +7) +3)
5 +(6 +4 +7) +3
5 +(6 +4) +(7 +3) . . . . . groups "tens" together
(5 +6) +4 +(7 +3)
5 and 13
(9 + 6i) - (1 + 3i) = 9 + 6i - 1 - 3i = (9 - 1) + (6i - 3i) = 8 + 3i