You will be given a problem involving the mixing of two beakers of acid.  After typing in a step, hit the "Enter" key.  For the last column in the table and in the equation, do not multiply the expression out unless you are multiplying by 0 or 1.  For example, write expressions as .09(7-x), but if the expression is 1(7-x) or 0(7-x) write it as 7-x or 0 respectively.  This activity will ask you to complete 12 mixing problems.  It should get easier as you become more experienced.  In order to succeed with this activity, it is expected that you already know how to solve linear equations.  If you need help, click on the "Hint" button.  Good luck!