Hey there !
Let us take the length of the shorter piece as ' x '
Then, the longer piece would be ' 3 + 5x '
Total = 45
x + 5x + 3 = 45
6x + 3 = 45
Subtracting 3 on both sides
6x = 42
dividing by 6 on both sides
x = 7
shorter wire = 7 ft
longer = 45 - 7
= 38 ft
Hope my answer helps!