Of the three numbers, the sum of the first two is 45; the sum of the second and the third is 55 and the sum of the third and thrice the first is 90. The third number is Select: A) 10 B) 20 C) 30 D) 40 E) 50
Solution   Let the number be x, y and Z.   = Then, x+y=45, y+z=55&amp;3x+z=90   ‹=›y=45-x, z=55-y = 55-(45-x) = 10+x   ‹=›Therefore 3x+10+x = 90 or x = 20.   y=(45-20)= 
<gadget id="calculator">(45-20)</gadget>
<output>25</output>
25 and z=(10+20)= 
<gadget id="calculator">(10+20)</gadget>
<output>30</output>
30.   Therefore Third number= 30   Answer 30
<result>C</result>
Of the three numbers, the sum of the first two is 45; the sum of the second and the third is 55 and the sum of the third and thrice the first is 90. The third number is