The time each train goes in 1 hour will be represented as a / b. b is 30 more than a, so if we add 30 to a it should equal b. a + 30 = b In three hours, the trains are 330 miles apart. Esentially, we're adding up the distance each train goes from the starting point to find the distance between them. 3b + 3a = 330 Now we have a system of equations to solve. a + 30 = b 3b + 3a = 330 We want to get the variables on seperate sides of the equation for easy solving. a + 30 = b 3b = 330 - 3a Then get the value of the one variable the same so we can use the transitive property. a + 30 = b b = 110 - a
