A particle C C\,C moves with constant acceleration (3i−5j) ms−2(3\mathbf{i} - 5\mathbf{j}) \text{ ms}^{-2}(3i−5j) ms−2. At time t=0t = 0t=0, C C\,C has speed u ms−1u \text{ ms}^{-1}u ms−1. At time t=4 st = 4 \text{ s}t=4 s, C C\,C has velocity (5i+4j) ms−1(5\mathbf{i} + 4\mathbf{j}) \text{ ms}^{-1}(5i+4j) ms−1.
Find the value of uuu.