= -15m-12n+48m-32n=33m-44n
...................вроде так
<span>7/13+1/13=8/13
</span><span>3/10+1/7=31/70
</span>9/25+2/5=0.76
<span>1/25+3/35=22/175
</span><span>5/7-2/7=3/7
</span><span>7/9-1/4=19/36
</span><span>7/8-5/7=9/56
</span><span>7/24-7/36=7/72</span>