I HAVE STRUGGLED to understand the algebra about how the final p=30-(6*q/5) was obtained, please explain

EXAMPLE 5.3 Smith and Jones are the only consumers in the market for lamb chops in a small town in Wales. Their (inverse) demand curves are given by P = 30 - 2Q; and P = 30 - 3Qs where, Q] and Q5 are the quantities demanded by Jones and Smith, respectively, at price P. What is the market demand curve for lamb chops in their town? When we add demand curves horizontally, we are adding quantities, not prices. Thus it is necessary rst to solve the individual demand equations for the respective quantities in terms of price. This yields Q J: 15 (P/2) for Jones, and Q5 = 10 (P/3) for Smith. If the quantity demanded in the market is denoted by Q, we have Q = Q J+ Q5 = 15 (P/2) + 10 (P/3) = 25 - (SP/6). Solving back for P, we get the equation for the market demand curve: P = 30 (6Q/5). We can easily verify that this is the correct market demand curve by adding the individual demand curves graphically, as in Figure 5.16