If x + 51 equals 17, then x must be negative. (If we are going to add 51 to some number and only get 17, an number less than 51, then we had to start at a negative number for this to happen.) Let's work through this one.
x + 51 = 17
x = 17 - 51 (we subtracted 51 from both sides of the equation)
x = -34 (we have arrived at the answer)
1 x 51, 3 x 17, 17 x 3, 51 x 1
1 x 51, 3 x 17, 17 x 3, 51 x 1
1 x 51, 3 x 17, 17 x 3, 51 x 1 = 51
1 x 51, 3 x 17, 17 x 3, 51 x 1 = 51
1 x 51, 3 x 17.
1 x 51, 3 x 17 = 51
1 x 51, 3 x 17, 17 x 3, 51 x 1.
51
1 x 51, 3 x 17
75
5
51.