Well you have to add 5+7+3=15 options, and you'd choose 3 of the 15 options
If you are trying to find x it is x=15-y
Answer: 10n^2 - 10
Step-by-step explanation:
(5n - 5)(2+2n) becomes (5n-5)(2n+2)
= (5n)(2n) + (5n)(2) + (-5)(2n) + (-5)(2)
= 10n^2 - 10
They made 12 because 7 plus 5 equals 12