Most economic solution

I'll be brutally honest with you guys but I'm here just for a simple suggestion concerning a very basic and poor audio setup.
Here's the problem: I have to give a presentation which requires audio projection both from a microphone (my voice) and a pc (music/powerpoint audio), so I thought to use something I already have, which is a Sony Micro HI-FI system (CMT-EH25, pdf manual: https://www.sony.com/electronics/support/res/manuals/3874/38742795M.pdf) and a 10€ microphone previously ordered from Amazon (NGS Singer Fire, Amazon link: https://www.amazon.it/NGS-Singer-Ka...1718879287&sprefix=NGS+SInger+,aps,120&sr=8-1).
I thought I could buy a simple mixer so that it could receive as input both the mic sound and the pc music and output both of them as one, connecting the mixer to the 3.5mm jack of the Sony system: precisely I bought this one on Amazon https://www.amazon.it/dp/B0B6CTHW79?psc=1&ref=ppx_yo2ov_dt_b_product_details (it was on sale at only 13€).
I later realised the microphone doesn't work because the mixer doesn't have a microphone input, and made the potential mistake of returning it before realising I could buy a mic preamplifier to attach between the mic and the mixer.
I ask for the simplest and cheaper solution to my problem, between buying a mixer with microphone input, buying a mixer with no mic input + a preamplifier, or anything else that works.
Thanks a lot

 

Mixers with mic input from brands such as Behringer and Samson start at around £40-£50. Alternatively you could approach a PA hire company and they will be able to both advise and to rent you the equipment.