An airplane travels 2100 km at a speed of 500 km/hr encounters a head wind that decreases its speed to 400km/h for the next three hours and then travels the last 400km to complete the trip at an average speed for the entire trip of 440 km/h what was the speed of the plane for the last part of the trip

3

step-by-step explanation:

in standard form:

a= dictionaries

b= maps

you have to buy 3 dictionaries, so put a 3 next to the a (dictionaries) so that you can multiply them by each other.

a3+b= 60 (the amount of money you have)

we already know the cost of a=15 so replace a with $15

($15 x 3)+b=60

multiply 15 and 3 to get $45 and replace it with $45

45+b=60

and then replace b with 15 to get the total:

45+15=60

that means you have $15 left after buying 3 dictionaries.

15 divided by the cost of a map ($5) equals 3.

so you can buy 3 maps.

sorry if it was confusing!

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step-by-step explanation: