Answer:
its obvious that 1 t shirt cost 6 dollar. so for 10 t shirts it will be 10×6 = 60 dollars. Since they want the # of t shirts to be s then its s × 6 or 6s or 6 × s
I would say that the 15 foot tree would cast a 6 foot shadow. I say this because for every 5 feet of an object, it is two inches of a shadow.
5 foot flagpole - 2 foot shadow
10 foot flagpole - 4 foot shadow
15 foot tree - 6 foot shadow
It'd be 4.25 * 10^4. The rule is that the number has to be less than 10 then has to be multiplied by a power of 10, ie. 100 = 1 * 10^2