Problem Solving using Linear Systems

Question

The units digit of a two-digit number is 1 less than 3 times the tens digit. If the digits are reversed, the new number is 45 more than the original number. Find the number.

Answer 1

u: units digit , t: tens digit

u = 3t - 1

10u + t = 10t + u + 45

Because u is isolated in the 1st equation, solving by substitution will be easy:

10(3t - 1) + t = 10t + (3t - 1) + 45 ...