[tex]-\frac{1}{4}+\frac{3}{4}a=-\left(-\frac{7}{4}a-1 \right)[/tex]
Multiplying both sides by 4,
[tex]-1+3a=-(-7a-4)\\\\-1+3a=7a+4\\\\-1=4a+4\\\\-5=4a\\ \\ a=\boxed{-1.25}[/tex]