Answer:
K - Constant of proportionality
Y/X = K
Step-by-step explanation:
Can’t see the graph but the first point can be calculated. If your first point is (100,78) that’s (x,y), your k = 78/100, $78 US dollars and 100 euros, thus the unit rate is 78/100 = 0.78/1 which means 0.78 dollars equals 1 euro.