YAY, I love these. Been doing them in class for the past month:
4x+7y=1 #first equation
3x+10y=15 #second equation
Ok first of all you need to find a common number\multiple for either X or Y.
I'm choosing X because they are easier numbers
First Eqn * 3 = 12x + 21y = 3
Second Eqn * 4 = 12x + 40y = 60
So now we can do one or two things: rearrange either to get something like "x=5-y" and then substitute into the equation, or we can subtract them both (which is easier):
So i'm going to subtract them both (this is called the elimination method)
12x + 21y = 3
-(12x + 40y = 60)
-19y = -57
19y = 57
y = 57/19
y = 3
Now we know y=3 we put this into any equation we have gotten and then solve for "x"
4x + 7(3) = 1
4x + 21 = 1
4x = -20
x = -5
To conclude, y=3 x=-5
Sorry if the spacing is bad, writing this on my phone