Help with some calculations

Question

My question is: what I need to do to get 2nd equation from the first?

1)

$TP1 = vp1 · λ + TS1$
$TP2 = vp2 · λ + TS2$

2)$$TP_2 − TS_2 =\frac{vp2}{vp1}(TP1 − TS1)$$

Answer 1

Hint: Look at the two equations, which terms are missing when you go from 1) to 2). Try to eliminate that term.