Bob is packing a suitcase to take on an airplane. A suitcase and its contents can weigh at most 50 pounds before the airlines charge extra fees. Bob's suitcase weighs 10 pounds when it is empty, so he can put 40 pounds of clothes in the suitcase. Bob's shirts weigh 0.5 pounds each and his pants weigh 2 pounds each.
**
Write an equation that would model how many pounds of clothing Bob can pack.
Rewrite the equation to model the number of pants Bob can pack in terms of the number of shirts.