Pretty sure it’s 4. Hope this helped :)
It would take Emily a little over 6 hours to get to her friends house.
Hey there!!
Basic formula :
... a² - b² = ( a + b ) ( a - b )
Equation given :
... 81x² - 25
... ( 9x )² - ( 5 )²
... ( 9x + 5 ) ( 9x - 5 )
Hope it helps!!