substitutuion method for 5s-2t=16 and s+3t=10
s + 3t = 10
s = 10 - 3t
Now you have something you can substitute
into the first equation.
5s - 2t = 16
5(10 - 3t) - 2t = 16
50 - 15t - 2t = 16
50 - 17t = 16
-17t = 16 - 50
-17t = -34
t = 2
Substitute that into the second equation.
s + 3t = 10
s + 3(2) = 10
s + 6 = 10
s = 10 - 6
s = 4
s = 4 and t = 2