Ali scored 9 Goals while Hani scored 4
Let the goals scored by Ali = x
Let the goals scored by Hani = y
So, if Ali scored 5 more goals than Hani then it can be written as
x= y+5 ....(1)
They scored 13 goals together so,
x+y=13 ......(2)
Substituting the value of x in equation 2
x + y+13
y+5+y=13
5 + 2y = 13
2y = 13-5
2y = 8
y = 8/2
y = 4
x = 4+5 = 9
--------------
= (x + y)x - (x + y)y [Distributive property]
= x(x + y) - y(x + y) [Commutative property]
= xx + xy - yx - yy [Associative property]
= xx + xy - xy - yy [Commutative property]
= xx + (xy - xy) - yy [Associative property]
= x² - y² [Subtraction]