3x - y - 5 = 0, and 7x - y - 3 = 0

Rearrange both equations to the slope-intercept form

y = 3x - 5

y = 7x - 3

So that, m\(_1\) = 3, and m\(_2\) = 7

Tan \(\theta\) = \(\frac{m_2 - m_1}{1 + m_1 m_2}\)

\(\theta\) = tan\(^{-1}\)[\(\frac{m_2 - m_1}{1 + m_1 m_2}\)] = tan\(^{-1}\)[\(\frac{7 - 3}{1 + 7 \times 3}\)]

\(\theta\) = tan\(^{-1}\)[\(\frac{4}{22}\)] = 10.3 ≈ 10º

Thus, the acute angle between the two lines is approximately 10º