Answer: Alex has $77 more than Amy
Step-by-step explanation:
Draw a vertical number line. Plot -28 and 45 on this number line. Also, plot the number 0. Note the distance from -28 to 0 is 28 units. Then from 0 to 45 is another 45 units.
Overall, the distance is 28+45 = 77 units. This is the distance between the points -28 and 45 on the number line. It indicates Alex has $77 more compared to Amy. Effectively, Amy has $0 right now, but she's in debt $28. If we ignored the debt temporarily, then Alex has $45 more compared to Amy's balance of $0. Then we tack on the debt of 28 to bump to $77.
Another way to see this is to consider that Amy somehow gets $28. That 28 dollars is then immediately paid back to bring the balance back to $0. Then we'll tack on the $45 to get to 45+28 = 77.