Answer:
550a + 590b = 1275
Step-by-step explanation:
We use the following relation to solve this question:

In which v is the velocity, d is the distance and t is the speed.
In this question, we find the distance, so we use:

A plane is flying to Metro City. The plane started its journey 1275 miles from Metro City.
This means that
.
Write an equation in standard form to represent the situation if the plane travels a hours at 550 mph and b hours at 590 mph.
This means that
.
Which equation is correctly written in standard form to represent this scenario?

1275 = 550a + 590b
550a + 590b = 1275