How do you justify

10 (y+5) = 10

I don't really know what you mean when you say "justify".

That's an equation in 'y'. There's only one number that

'y' can be if the equation is a true statement.

The number is - 4. It's called the "solution" of the equation.

Want a word problem for it

if u do it's 10of y plus 5 is 10