1+6 = 7 *3 = 21 no good

2+7 = 9 *3 = 27 YES !

Solved

Not knowing either digit and not knowing the number but knowing that the units digit was 5 more than the tens digit, you’d call the tens digit “n”. Since the units digit is 5 more than that, you’d call the units digit “n+5” (since you don’t know what it is, only that it’s 5 more than the tens digit. Then you find the sum of the digits by adding “n” and “n+5”. The result is “2n+5”. Since the number you’re looking for is 3X the sum of the digits (which is “2n+5”), you’d multiply “2n+5” by “3” and get “6n+15”. Then you plug in numbers starting from ‘0’ until you find a number whose units digit is 5 more than its tens digit. To find this fortunately doesn’t take very long because when you plug ‘2’ into the equation, you get (6×2)+15 which is equal to 27. You’re still not done, though, because there can be many numbers whose units digit is 5 more than its tens digit but are not 3 times the sum of its digits. Fortunately in this case, however, you need look no further because “27” IS 3X the sum of it’s digits. The sum of the digits is ‘9’ (2+7) and 27 is ‘3 times 9’.

Matt

so the digit at units place will be x+5

the number is 10*x+x+5=3(x+x+5)

or 10x=3(2x+5)-x-5

or 10x=6x+15-x-5

or 10x=5x+10

or 10x-5x=10

or 5x=10

or x=10/5

or x = 2

Let the number be 10x+y

y = x+5 and, 10x+y = 3(x+y)

7x = 2y, then 7x = 2x+10 ; x = 2, y = 7

Number is 27