Physics
posted by Kristina .
A golfer rides in a golf cart at an average speed of 3.10 m/s for 21.0 s. She then gets out of the cart and starts walking at an average speed of 1.60 m/s. For how long (in seconds) must she walk if her average speed for the entire trip, riding and walking, is 2.10 m/s?

Require that
2.10 (T+21) = 3.1*21 + 1.6*T
= (total distance travelled)
Then solve for T, which will be in seconds. 
I need help solving for T!!!

2.10(T+21)=3.1*21+1.6T
What kind of help do you need in solving for T? 
2.1T + 44.1 = 65.1 + 1.6 T
0.5 T = 21
Can you complete the solution?
One should learn algebra before studying physics