Which math statement does not contain a variable?

a. 17 - 17 = 0

b. 40 - d = 36
c. x+ m = 19

d. 13 + x = 15

The hawaiian alphabet has 12 letters. how many permutations are posible for each number of letters?

The volume of gas a balloon can hold varies directly as the cube of its radius. imagine a balloon with a radius of 3 inches can hold 81 cubic inches of gas. how many cubic inches of gas must be released to reduce the radius down to 2 inches?

Let hh represent the number of hummingbirds and ss represent the number of sunbirds that must pollinate the colony so it can survive until next year. 6h+4s > 746h+4s> 74 this year, 88 hummingbirds pollinated the colony. what is the least number of sunbirds that must pollinate the colony to ensure that it will survive until next year?