Thank you for the opportunity to help you with your question!

Hello Zoe

to solve:

cross multiply the denominators and the numerators, like this

-4a (a-17)=12 (a-17)

then open the brackets like this:

= -4a^2 + 68a = 12a-204

then, put like terms together to get

-4a^2 + 68a -12a + 204 = 0

to give you

-4a^2 + 56a + 204 = 0

divide all through by 4 to get:

-a^2 + 14a + 51 = 0

Change the sign on first root to get:

a^2 - 14a - 51 = 0

after this, use the various methods of solving quadratic equations, mainly the formula one.

Hope this did assist. Please let me know if you need any clarification. I'm always happy to answer your questions. I will be pleased if you make me your private tutor.
Thank you