The sum of digit of a number 10 to the power n minus 7 is 3792 then what is the value of n

I'm being volume of cylinder with 13 in. radius and 30 in height answer choices in pic

Three cylinders have a volume of 2836 cm^3. cylinder a has a height of 900 cm. cylinder b has a height of 225 cm. cylinder c has a height of 100 cm. find the radius of each cylinder. use 3.14 as an approximate for π

Which shows the correct substitution of the values a,b and c from the equation 1=-2x+3x^2+1