There's a class of puzzles that require the solver to arrange a set of numbers so that they result in a desired outcome by manipulating mathematical operators. Example:
Using the numbers [1,3,5,7,9] find an equation that results in 31
which could be solved as
(9 * 5) - 7 * (3 - 1) = 31
Is there a specific term for this type of puzzle and if so what is it?