Question

.05x+.25y=66
.15x+.05y=72

Answer 1

(420,180)

Answer 2

multiply the first line by -3 (to cancel out the x) or by -5 (to cancel out the y) and then add both lines.

-.15x + -.75y = -198
+ .15x + .05y = 72
= -.70y = -126
= y = 180

Now you have y, so you can substitute it in one of the original equations and solve for x.

Answer 3

You can also divide the second line by -3 (to cancel out the x) or by -5 (to cancel out the y). You can manipulate them as you wish in order to get a variable to cancel out when you add both equations.