Question 468514: the tenth digit of a two digit no. is 5 more than the unit digit. what is the number if the sum of two digit is 9.
Answer by rfadrogane(214)   (Show Source):
You can put this solution on YOUR website! the tenth digit of a two digit no. is 5 more than the unit digit. what is the number if the sum of two digit is 9.
Solution;
let: t - the ten's digit
u- the unit digit
N - the number
N = 10t + u
from first phrase:
t = 5 + u <-----(1)
from second phrase:
t + u = 9 <-----(2)
substitute (1) into (2),
(5 + u)+ u = 9
2u = 9 - 5
2u = 4, divide 2 on both side to obtain the value of u,
u = 2
for t:
t = 9 - 2 = 7
Thus a number is
N = 10(7) + 2
N = 72 <----- answer
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