Question

2x+3.5y=355 2x+3y=320

Answer 1

I guess what you need to know is where do the two equations meet.

Start by subtracting the bottom from the top. 2x will than cancel out.

0.5 y = 35 Divide by 0.5
y = 35 /0.5
y = 70

Now you can get x.
Put 70 in for y into the second equation.
2x +3*70 = 320
2x + 210 = 320 Subtract
2x = 320 - 210
2x = 110 Now divide by 2
x = 55

Check
======
You should check these.
2*55 + 3.5*70 =? 355
110 + 245 =? 355
355 =! 355

It does check out.