The amount of the element remaining (y) in grams after time (t) in minutes is defined by the equation y=970(1-.151)^t. Substitute t=14 into the equation and solve for y. y=970(.849)^14=98.06 rounded to two decimal places.
So he bought the $120 game with $82 and 2 equally priced game. This can be changed to an equation: 120= 82+2X. The X represents the cost of the used game. 120= 82+2X -82 -82 ——————- 38= 2X