A+b+c= 180 <span>a = ? </span><span>b = 2a - 10 (twice a minus 10) </span><span>c = b + 25 (25 more than b) </span><span>Substitute for b c = (2a-10) + 25 </span><span>Now substitute back into a+b+c=180 a + (2a-10) + (2a-10+25) = 180 </span><span>Eliminate the parentheses a + 2a - 10 + 2a - 10 + 25 = 180 </span><span>Combine like terms 5a + 5 = 180 </span><span>Subtract 5 from both sides 5a = 175 </span><span>Divide both sides by 5 a = 35 </span><span>Substitute into the equation for b. b = 2a -10 = 2*35 - 10 = 70 - 10 = 60 </span><span>Add 25 to b to get c. c = 60 + 25 = 85</span><span>Check by adding them up. 35 + 60 + 85 = 180 Done.</span>