Values for the function f(x) are given in the table below. Use it to solve the equation $\displaystyle {f{{\left({x}\right)}}}={7}$

x	-7	-6	-5	-4	-3	-2	-1	0	1	2	3	4	5	6	7
f(x)	31	29	27	25	23	21	19	17	15	13	11	9	7	5	3

x=