How do you solve #x=3y+2# and #x+y=10# by substitution?
1 Answer
Apr 28, 2016
The easiest way is to make x the subject in each case and then equate the two right hand sides to each other.
Explanation:
There are two different ways in which you can write x.
x is already given as being equal to 3y + 2, but from the other equation, x can also be written as 10-y. But because x = x, the expressions for x must also be equal to each other:
hence 3y + 2 = 10 - y. This solves to give y = 2. There are now two different ways to find the value for x. They both give x to be 8. Test both to make sure you get the same answer. x = 8 and y = 2.
