Substitute the values. 
Follow PEMDAS and multiply and divide first. 
Continue following PEMDAS and subtract. 
The best way to solve this problem is to graph all variables, velocity being the dependent variable (y-axis) and time being the independent variable (x-axis) . Since we are given two points for the two variables, we use the point-slope formula to get the slope which happens to be -1. We then use the standard form y = mx + b and substitute m with -1. Next we want to find b, we will again use the point slope formula now knowing m to be -1. we chose point 0 for time(x-axis) and at zero, we obtain a value of your b which happens to be +19. A line graph would better visualize my point. Cheers!
The theorem tells you angles complementary to the same angle are congruent. Both 4 and 1 are complementary to 5, so 4 and 1 are congruent.
The angle congruent to 4 is 1.
Hey, I think an image is needed to answer this question.
