We can write out a formula in order to solve this. Since sum represents addition, if x represents the unknown number, we can write the formula: x+51=-21. Then, to solve for x, you would subtract 51 from both sides to get x=-72 which is the final answer.
To compare the numbers, go from left to right examining the numbers carefully. so look at a., 3.7 can be written as 3.700, if u look, 3 and 0, it is definetly bigger than 0.01 and 0.001
You either find the gradient or distance and if there are equal, therefore the opp are equal
