Answer:
(I). The sum of the vectors is (7i-5j).
(II). The sum of the vectors is (8i+7j).
Step-by-step explanation:
Given that,
(I). Vector A

Vector B

Suppose, (II). Vector A

Vector B

(I). We need to calculate the sum of the vectors
Using formula of sum

Where,


![\vec{C}= sum of the vector A and b</p><p>Put the value into the formula</p><p>[tex]\vec{C}=(3i-12j)+(4i+7j)](https://img.qammunity.org/2021/formulas/physics/college/cok791dakfo1rvk4jcbiwvteqepgw3rf2k.png)

(II). We need to calculate the sum of the vectors
Using formula of sum

Put the value into the formula


Hence, The sum of the vectors is (7i-5j).
The sum of the vectors is (8i+7j).