Is there a proportional relationship between time and the amount of water left in the tank?

Yes

Step-by-step explanation:

y is the litters of water in the tank

x is the time in minutes

m is the change in litters

b is the initial amount of water

so the formula is y = mx + b

whereas m is -14 and b is 770

y = -14x + 770 or y = 770 - 14x

d. millimeters per hour.

step-by-step explanation:

we are given that,

carlo used a rain gauge to measure the amount of water his lawn is receiving from the sprinklers.

since, according to the options, we see that,

water cannot be measured by 'miles per hour', 'meters per second' and 'grams per seconds'.

we get that, the water can be measured by 'millimeters per hour'.

hence, the appropriate rate for describing the amount of water is 'millimeters per hour'.