In question #3, you combine the like term terms. In this example, 7q and -6q, as well as +8 and +13. Therefore, when you combine these terms, the solution is q + 21.
In question #4, the same method is used. You simply have to combine the like terms, only this time with another variable. The only terms to combine are: 3s + 4s = 7s. We are left with the following: 7s - 5t + 8.
