1) ( 7 7/12 - 15 ) - ( 18 1/2 - 13 7/15 )2) ( 5 + 3 5/8 ) - ( 7 3/4 - 23 ) 

[latex]( 7 \frac{7}{12} - 15 ) - ( 18 \frac{1}{2} - 13 \frac{7}{15} )=7 \frac{35}{60} - 15 - 18 \frac{30}{60}+ 13 \frac{28}{60} = \\\ =-13+ \frac{33}{60} =-12 \frac{27}{60} =-12,45[/latex] [latex]( 5 + 3 \frac{5}{8} ) - ( 7 \frac{3}{4} - 23 ) = 5 + 3 \frac{5}{8} - 7 \frac{6}{8}+ 23 = \\\ =24 - \frac{1}{8} =23 \frac{7}{8} =23,875[/latex]