Cześć ;-)
a)
[tex]4(2a+7)-(2a-5)=\\\\=8a+28-2a+5=\\\\=8a-2a+28+5=\boxed{6a+33}[/tex]
b)
[tex]5(3x-3)-(7x+6)=\\\\=15x-15-7x-6=\\\\=15x-7x-15-6=\boxed{8x-21}[/tex]
Pozdrawiam!