Use a app called photo math it works good.
So the problem ask to find or solve the problem using distributive property, so to calculate if using distributive property is just the same calculation if you are multiplying two number using a paper so the answer is 5(8)+5(90)+5(100), 40+ 450+500 = 990. I hope you understand my answer
5.6 the answer is obviously
Add 9x to both sides
3y=9x+15
Divide 3 to both sides to get y by itself
Y=3x+5
Easy, do 12 divided by 5 = 12/5
=
2.4
