21 Solve each of the following equations. (a) $4(x+1)-5(x+6)=3 x+4$ (b) $\frac{4 x+1}{3}-\frac{x-2}{4}=2$

Step 1 ：(a) Distribute and combine like terms: \(4(x+1)-5(x+6)=3x+4\) becomes \(-x-26=3x+4\)

Step 2 ：(a) Solve for x: \(x = \boxed{-\frac{15}{2}}\)

Step 3 ：(b) Find common denominator and combine fractions: \(\frac{4x+1}{3}-\frac{x-2}{4}=2\) becomes \(\frac{13x}{12} + \frac{5}{6} = 2\)

Step 4 ：(b) Solve for x: \(x = \boxed{\frac{14}{13}}\)