<span>25х + 15х =(25+15)х=40х</span>
<span><span>8m + m =9m</span></span>
<span><span><span>z + 19z =20z</span></span></span>
<span><span><span><span>12y -2y =(12-2)y=10y</span></span></span></span>
8b + b - 9b =(8+1-9)b=0
<span>4a - 3a + 5b- b =(4-3)a+(5-1)b=a+4b</span>
<span><span>7x + 3x + 43 =(7+3)x+43=10x+43</span></span>