<span>(R+5)*7-54=(R+5)*4</span>
<span>7R+35-54=4R+20</span>
<span>7R-4R=20-35+54</span>
<span>3R=39</span>
<span>R=39:3</span>
<span>R=13</span>
<span><span>17*(c-2)-36=19+(c-2)*12</span></span>
<span><span>17с-34-36=19+12с-24</span></span>
<span><span>17с-12с=19-24+34+36</span></span>
<span><span>5с=65</span></span>
<span><span>с=65:5</span></span>
<span><span>с=13</span></span>