We know the opposite side (10) and the adjacent side (7), so we can use tangent to find angle B. Since tan = opposite side/adjacent side, we can set up this equation: tan(B) = 10/7. We can get B on its own by making the equation this: 
Now, we plug this into our calculator to get:
B = 55°, so angle B is 55°.
Let me know if you need any more help!
Now, we plug this into our calculator to get:
B = 55°, so angle B is 55°.
Let me know if you need any more help!