Alexander B. answered • 10/24/15

Advanced Math and Science Tutoring and Test Prep online (SAT, ACT)

Let's assume the pair of unknown variables X and Y represents the speed of these two planes. The problem can be written as the following system of 2 linear equations:

4(X+Y)=2660

X-Y=65

or in canonical form:

4X + 4Y = 2660

X-Y= 65

It can be solved either manually or using online equations solver (http://examn8.com/SystemOfEquations.aspx), giving the answer: X=365 mph and Y=300 mph.