Answer:
ST = 4
Explanation:
Given that SU and GN are corresponding sides, then they are congruent.
SU = 3ST - 5 ( 5 less than 3 times ST )
GN = ST + 3 ( 3 more than ST ), thus
3ST - 5 = ST + 3 ( subtract ST from both sides )
2ST - 5 = 3 ( add 5 to both sides )
2ST = 8 ( divide both sides by 2 )
ST = 4