Hurley processes clay into $2$ joint products. When processed each pound clay yields $20$ units of foam and $80$n units of blocks. Foam sells for $$2$ per unit and blocks sell for $$1\mathrm{.}50$ per unit. The total costs to process a $100$ pound batch clay is $$35.$ If the physical quantities method is used to allocate the joint costs, how much will be allocated to each batch of modeling foam