Not the best, teachers are so annoying lol. Hope you are doing well though, don’t give up❤️
Answer:
22
Step-by-step explanation:
because i swiched the x's to the 7 and multipled
I think with the kinds of mixture problems, it's really helpful to make a table.
The equations you actually need are

and

. Since I was so close, I went ahead and just solved it anyway. You can see my setup on the attached image.
12=-12+x
or are you looking for something like you provided us in your question
"<span>(example 3x+4y=19 )"</span>