2 1/4 r =10?

Answer 1

2 1/4 r =10

r = 10 / (9/4)

r = 10 * (4/9)

r = 40/9 = 4 4/9

Answer 2

Ok but how does the 9/4 thing work?

Answer 3

2 * 4 = 8
8 + 1 = 9

2 1/4 = 9/4