Help

T= mv^2/r      Solve for 'v'    1st : Multiply both sides of the equation by 'r'

Tr = mv^2      Then divide both sides by 'm'

Tr/m = v^2     Take the sqrt of both sides

sqrt( Tr/m) = v  

Second one

Which of the combos provides for 112 desserts?

3 pies * 8 pieces/pie   +  8 batches * 12 pieces/batch  = 112?

        24 pieces   + 96 pieces = 120    does NOT equal 112        This will work with some desserts left over.........try the others to see if ONE of them equals 112 pieces......pick the one that provids at LEAST 112 pieces with the least amount left over.

Here's a graphical solution for the second one :

https://www.desmos.com/calculator/fnueaahoif

If we let  x be the number of pies and y be the number of batches of brownies.....we can graph the inequality 

8x + 12y ≤ 112

Lookng at the graph....we can forget the points inside the shaded area....these combinations will not yield enough desserts

Note that the red dot - representing 3 pies and 8 batches of brownies - is closer to the boundary of the inequality than the points (2, 9)   and (5,7)

So   

(3, 8)  yields = 120 desserts

(2, 9) yields = 124 desserts

(5, 7) yields = 124 desserts

So.....we want to choose   3 pies and 8 batches of brownies

Thanks to EP  for spotting my earlier error  !!!