Помогите с алгеброй !!!

Решите задачу:

$1)2b+ \frac{5a+-2b^2}{b} = \frac{2b^2}{b} + \frac{5a+-2b^2}{b}= \frac{2b^2+5a-2b^2}{b}= \frac{5a}{b } \\ a=6, b=-60, \frac{5*6}{-60} = -\frac{30}{60}=- \frac{1}{2}=-0,5 \\ 2) 7b+ \frac{2a-7b^2}{b} = \frac{7b^2}{b}+ \frac{2a-7b^2}{b}=\frac{7b^2+2a-7b^2}{b}= \frac{2a}{b} \\ a=9, b=12, \frac{2a}{b}=\frac{2*9}{12}= \frac{18}{12}= \frac{3}{2}=1,5 \\ 3)8a- \frac{8a^2-3c}{a} = \frac{8a^2}{a}- \frac{8a^2-3c}{a}= \frac{8a^2-8a^2+3c}{a}= \frac{3c}{a} \\ a=15, c=12, \frac{3*12}{15}= \frac{12}{5} =2,4$