The equation is basically asking, if you add 1 to a number, and it equals -3, then what number did you add to? To solve this just reverse the equation (subtract 1 from -3), which will get you -4.
Solve for t. Simply sense its +1, do the opposite and minus 1 from both sides of the equation. +1 - 1 = 0; -3 -1 = -4. Therefore, t = -4 is the correct solution.
