# How to solve substitution

2
by jsdg

2014-11-25T19:22:29+08:00
Change your variables(the letters, most of the time) to the proper constant (the numbers) and then proceed to doing the operations.
2014-11-25T20:44:14+08:00

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Let me state an example:

There are two consecutive even numbers. The sum of the two consecutive even numbers is 20. If the difference of the two numbers is 2, find the numbers.

Let:
x-be first number
x+2-second number

x+y=20
x-y=2

We can pick any equation and find the value of either of the variables, but I will select the second equation instead.
x-y=2
x=y+2

x+y=20
since the value of x is y+2, substitute the value.
y+2+y=20
2y+2=20
2y=18
y=9

Substitute the value of y in the value of x
x=y+2
x=9+2
x=11.

Hope this helps =)