What is the number?

Question

A certain two-digit number has a value that is three times the sum of its digits. The units digit is one more than three times the tens digit.

Answer 1

let ab be the number

10a+b=3(a+b)

b=3a+1

10a+b=3a+3b

10a-3a=3b-b

7a=2b

b=3a+1

substitute

7a=2(3a+1)

7a=6a+2

7a-6a=2

a=2

b=3*2+1

b=7

the number is 27