Solve this pair of simultaneous equations. 5x + 2y = 20 x + 4y= 13

One way to solve simultaneous equations is to express x in terms of y (or vice versa) and solve your new equation to find one of the values. You can then substitute this into your equation to work out the other unknown.

1. 5x + 2y = 20    2. x + 4y = 13 ----> from this equation, we know that x = 13 - 4y. Putting our new version of x into equation 1. we get ---> 5(13-4y) + 2y = 20. Multiply out the bracket and rearrange, ---> 65 - 20y + 2y = 20 ---> 65 - 18y = 20 ---> 18y = 45. y = 45/18 = 2.5. Now we know y = 2.5, we can find x by putting it back into equation 2. x + 4y = 13 ---> x + 10 = 13 so x = 3. To check our values for x and y are correct, we can use equation 1. 5x + 2y = 20 ---> 15 + 5 = 20. Therefore x = 3 and y = 2.5.