You will try to get t by itself. Start with adding 4.9t to both sides to get 7=15+12.5t Then subtract 15 from both sides to get -8=12.5t Divide both sides by 12.5t so you will get -0.64=t. Plug this back in to the equation to check your work. 7-4.9(-.64)=10.136 15+7.6(-.64)=10.136