Answer:
25x ²−49y ²
Step-by-step explanation:
We need to find product of (5x+7)(5x−7y)
By using identity (a+b)(a−b)=a −b ²
We have a=5x,b=7y
Thus (5x+7y)(5x−7y)=(5x) ²−(7y)
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10x= 23.333333333333
10x-x=9x=21
x=21\9=7/3