3T + 4S = - 2,5t-6s = 3 process,

3T + 4S = - 2,5t-6s = 3 process,

3t+4s=-2(1)
5t-6s=3(2)
(1) 3 + (2) × 2
9t+10t=-6+6；
19t=0；
t=0；
Bring in (1)
4s=-2；
s-1/2;
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To solve the equations 2s-3t = 8 (1) and 7s-5t = - 5 (2)
The detailed process is based on the format
Solving equations
2s-3t = 8 ① formula
7s-5t = - 5 ② formula

1 * 5-2 * 3 can get - 11S = 55, so s = - 5, and then substituting it into any equation can get t = - 6, so s = - 5, t = - 6

Solving the equations 4S + 3T = 25 17s-3t = 48

4s+3t=25 ①
17s-3t=48 ②
① + 2
21s=73
Then s = 73 / 21
Bring in 2
t=17×(73/21)-48
=(1241-1008)/21
=233/21
So the solution of the original equations is s = 72 / 21, t = 233 / 21