Answer:
(a)

(b) (5.05 m, 16.93 degrees wrt x-axis)
Step-by-step explanation:
Given:
= (3.00 m, 315 degrees wrt x-axis)
= (4.50 m, 53.0 degrees wrt x-axis)
Let us first fond out vector D and E in their rectangular form.

Similarly,

Part (a):
We can write the resultant vector R as below:

Part (b):

Since both the components of the resultant lie on the positive x and y axes. So, the resultant makes an acute angle with the positive x-axis.
So, R = (5.05 m, 16.93 degrees wrt x-axis)