Question

1/2x+1/3y=5 and 1/4x+y=10 solve this system by substitution

Answer 1

Answer:

  (x, y) = (4, 9)

Step-by-step explanation:

You can use the second equation to write an expression for y.

  y = 10 - 1/4x . . . . subtract 1/4x from the given 2nd equation

Now, substitute that for y in the first equation:

  1/2x + 1/3(10 -1/4x) = 5

  1/2x + 10/3 -1/12x = 5 . . . . eliminate parentheses

You can work this a couple of ways from here. One is to multiply by 12 to eliminate fractions. Another is to work with the numbers as they are. We'll do that, because we don't get enough practice doing arithmetic with fractions.

  5/12x = 5/3 . . . . . subtract 10/3

  x = (5/3)/(5/12) = 12/3 = 4

From above, we can use our expression for y:

  y = 10 - 1/4·4 = 9

The solution is (x, y) = (4, 9).