what is 3 1⁄8 − 1 7⁄8 =
\(3\frac18-1\frac78 \\~\\ =\,(3+\frac18)-(1+\frac78) \\~\\ =\,3+\frac18-1-\frac78 \\~\\ =\,3-1+\frac18-\frac78 \\~\\ =\,2-\frac68 \\~\\ =\,1+\frac88-\frac68 \\~\\ =\,1+\frac28 \\~\\ =\,1\frac14\)
[(3*8+1 )/8 ] - [(8*1+7)/8]
[25/8] - [15/8]
[25 - 15] / 8
10 / 8
1 2/8 =1 1/4