Question 134137
Three digit number, so the digits are h for hundreds, t for tens, and o for ones.


The sum of the last two digits is 7:  {{{t + o = 7}}}
The sum of the first two digits is 5: {{{h + t = 5}}}
The middle digit is 4 times the first digit:  {{{t=4h}}}


We can substitute {{{t=4h}}} for {{{t}}} in {{{h + t = 5}}} giving us {{{h+4h=5}}}, and solve for h: {{{5h=5}}} => {{{h=1}}}


Knowing that {{{h=1}}} we can use {{{h+t=5}}} to determine that {{{t=4}}}.


Knowing that {{{t=4}}} we can use {{{t+o=7}}} to determine that {{{o=3}}}.


Therefore the number is 143.

4 + 3 = 7
4 + 1 = 5, and
4 = 4(1)

Answer checks.