Grace travels in an airplane a distance of 3480 km. For one-fourth of the distance, the airplane flies at a speed of 960 km/h, and for the rest of the distance, it flies at a speed of 680 km/h. How long does the trip take?

the answer is 844

step-by-step explanation:

it is 844 because if you add 836.50 + 7.5 you will get 844

proportions are fractions that equal to each other. so if two fractions are the same, they are proportional.

let's check the answers to see if they are proportional.

question a is not proportional because you can't turn 1.5/3 to 3/9. if you try to multiply 1.5/3 by 2 or 3, you wont get 3/9. it's impossible to make the fractions the same.

question b is not proportional because you can't turn 22/33 to 4/6. 33 can't go into 6.

question c is proportional because when you multiply 2 and 3 by 71, you would get 142/213, and those fractions equal to each other

question d is proportional because when you divide 14 and 7 by 2, you would end up with 7/3.5, and those fractions equal to each other.