we dont know what is the two numbers so let us assume that one is x and other is y
so the sum of two numbers will be x+y which is equal to 51
[tex] x+y=51 [/tex]
and their difference is 9
[tex] x-y=9 [/tex]
so now we have two equations we can solve this by elimination method.
[tex] x+y=51
x-y=9 [/tex]
we know that we have -y and +y which is same value with opposite sign so we can cancel it and x+x will be 2x and 51+9=60
[tex] 2x=60
x=30 [/tex]
we can plug x=30 in any one of the equations
[tex] x+y=51
30+y=51
y=21 [/tex]
[tex] x=30, y=21 [/tex]
