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)dIn the mapping, Un=y and n=x and U1, the first value of yU1=4y=4+(x−1)dThe d is the interval between each consecutive yIn this mapping, d=2−4=0−2=−2−0=−4−(−2)=−2We can substitute our d and simplify the expression for yy=4+(x−1)dy=4+(x−1)(−2)y=4+−2x−1×−2y=4+−2x+2y=4+2−2xy=6+−2xy=−2x+6