I need help with algebra substitution
3x-y=4 and 7x-2y=10

The shortest way would be to substitute the first equation into the second. And to do this, you will need to make y the subject of formula for the shortest way.

Can you do that first?

Try transforming this equation : 3x-y=4 so that you have y=something. Then you can plug that y into the second equation and solve. I'll check back to see if you get that first part and help you through the rest :)