randRange( 2, 10 ) randRange( 1, N1 - 1 ) randRange( 10, 20 )

fraction( N1, D ) - fraction( N2, D ) = {?}

( N1 - N2 ) / D
init({ range: [ [-3, 3], [-3, 3] ], scale: 25 }); PIECH = piechart( [ N1, D - 1 ], ["#e00", "#999"], 2 );
init({ range: [ [-3, 3], [-3, 3] ], scale: 25 }); piechart( [ N1-N2,N2, D - 1 ], ["#e00","#122", "#999"], 2 );

Subtract the numerators.

init({ range: [ [-3, 3], [-3, 3] ], scale: 25 }); piechart( [ N1 - N2, D - 1 ], ["#e00", "#999"], 2 );

fraction( N1, D ) - fraction( N2, D ) = fraction( N1 - N2, D )

Simplify.

init({ range: [ [-3, 3], [-3, 3] ], scale: 25 }); piechart( [ reduce(N1 - N2 , D)[0] , reduce(N1 - N2, D)[1] - 1 ], ["#e00", "#999"], 2 );

fraction( N1 - N2, D ) = fractionReduce( N1 - N2, D )