Note: If the mapping has equal interval (difference) for the y and x interval of 1 , you can use the general linear sequence formula to find the rule of the mapping. Un=U1+(n−1)d In the mapping, Un=y and n=x and U1, the first value of y U1=7 y=7+(x−1)d The d is the interval between each consecutive y In this mapping, d=11−7=15−11=19−15=23−19=4 We can substitute our d and simplify the expression for y y=7+(x−1)d y=7+(x−1)4 y=7+4×x−1×4 y=7+4x−4 y=7−4+4x y=3++4x y=4x+3