A certain number between 10 and 100 is 8 times the number of its digits and if the 45 is subtracted from it the digits will be reversed find the number
Answers
Answered by
10
let the number be xy
value of number = 10x+y
10x+y = 8(x+y)
10x+y =8x+8y
2x-7y=0....................(1)
10x+y-45 = 10y+x
9x-9y=45
x-y = 5.................(2)
multiply by -2
-2x+2y=-10
add to (1)
-5y=-10
y=2
x-y =5
x=7
Number = 72
value of number = 10x+y
10x+y = 8(x+y)
10x+y =8x+8y
2x-7y=0....................(1)
10x+y-45 = 10y+x
9x-9y=45
x-y = 5.................(2)
multiply by -2
-2x+2y=-10
add to (1)
-5y=-10
y=2
x-y =5
x=7
Number = 72
ut809:
why to mutiply by -2
Similar questions