Question

A combination of locks requires 3 numbers to open. The second number is 2d + 5 greater than the first number. The third number is 3d - 20 less than the second number. The sum of the three numbers is 10d + 9. find the first number.​

Answer 1

Answer:

Let the first number be x

Then, second number = x+2d+5

Third number = x+2d+5−(3d−20) = x−d+25

Sum of the three numbers = x+x+2d+5+x−d+25 = 3x+d+30

Thus, 3x+d+30 = 10d+9

3x=10d+9−d−30 = 9d−21

x=3d−7