Mathematics

If 55x + 52x = 7710 find X

If 55x + 52x = 7710 find X
  • A.
    5
  • B.
    6
  • C.
    7
  • D.
    10
Correct Answer: Option C
Explanation

5*X1 + 5*Xo + 5*X1 + 2*Xo = 77 (change to base 10)
5*X + 5*1 + 5*X + 2*1 = 77
5X + 5 + 5X + 2 = 77
10X + 7 = 77
10X = 77-7
10X = 70
X = 70/10
X = 7