2 + 462 : [ 10 × ( x + 20 ) : 2 + 1 ] = 4
462 : [ 10 × ( x + 20 ) : 2 + 1 ] = 4 - 2
462 : [ 10 × ( x + 20 ) : 2 + 1 ] = 2
10 × ( x + 20 ) : 2 + 1 = 462 : 2
10 × ( x + 20 ) : 2 + 1 = 231
10 × ( x + 20 ) : 2 = 231 - 1
10 × ( x + 20 ) : 2 = 230
10 × ( x + 20 ) = 230 × 2
10 × ( x + 20 ) = 460
x + 20 = 460 : 10
x + 20 = 46
x = 46 - 20
x = 26
