Which math statement does not contain a variable?

a. 17 - 17 = 0

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

d. 13 + x = 15

In a class, there are 12 girls. if the ratio of boys to girls is 5: 4 how many boys are there in the class

Using only odd number for numerators write two different subtraction problems that have a difference of 3/4

The perimeter of an equilateral triangle is 4 cm more than the perimeter of a square and the length of a side of the triangle is 8 cm more than the length of a side of the aware. find the length of a side of the equilateral triangle