X + 3y = 14
x + 3(3x - 14) = 14
x + 9x - 42 = 14
10x - 42 = 14
<u> + 42 + 42</u>
<u>10x</u> = <u>56</u>
10 10
x = 5.6
5.6 + 3y = 14
<u>- 5.6 - 5.6</u>
<u>3y</u> = <u>8.4</u>
3 3
y = 2.7
(x, y) = (2.7, 5.6)
Answer:
20 mph
Step-by-step explanation:
Let speed of Train a = Va mph
Let speed of Train b = Vb mph
Va = Vb + 30
Let time taken for Train a = Ta
Let time taken for Train b = Tb
time taken = distance travelled/speed
Ta = 350/Va = 350/(Vb+30)
Tb = 140/Vb
But they both travel in the same amount of time.
So, Ta = Tb

Cross multiply

Divide both sides by 210
