¯¯¯¯4 fiftieths plus 3 fifths equals blank 23− 712¯¯¯¯¯¯¯¯2 thirds minus 7 twelfths equals blank 910+ 2100¯¯¯¯¯¯¯¯¯9 tenths plus 2 100ths equals blank 49+ 14¯¯¯¯¯¯¯4 ninths plus 1 fourth equals blank 1715−1317 over 15 , minus , 1 third 716+387 sixteenths , plus , 3 eighths 25+142 fifths , plus , 1 fourth 17+121 seventh , plus , 1 half 12−3161 half , minus , 3 sixteenths 78−237 eighths , minus , 2 thirds 1112−4611 over 12 , minus , 4 sixths 718+597 eighteenths , plus , 5 ninths (78+112)−12open . 7 eighths , plus , 1 twelfth . close . minus , 1 half (1118−49)+16open . 11 over 18 , minus , 4 ninths . close . plus , 1 sixth 1314−(12+27)13 over 14 , minus . open . 1 half , plus , 2 sevenths . close 16+(1515−710)