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
