Question 1031695
Call the numbers of fast and slow, x and y.  Then we can write
10x = 2y - 140
and
(1/2)y = 3x + 10
Now double this and plug it in to the first equation and get
y = 6x + 20 and
10x = 2(6x + 20) - 140
10x = 12x + 40 - 140
10x = 12x - 100
-2x = -100
x = 50 fast
y = 6(50) + 20 = 320 slow