How do you solve the following system using substitution?: 3s5t=30,7s+11t=32

1 Answer
Oct 23, 2015

(s,t)=(52,92)=(212,412)

Explanation:

Given
[1]XXX3s5t=30
[2]XXX7s+11t=32

Rewriting [1] to generate an equation of the form: s= some expression
[3]XXX3s=5t30

[4]XXXs=5t303

We can now substitute (as per the question) (5t303) for s in [2]
[5]XXX7(5t303)+11t=32

Simplifying
[6]XXX35t210+33t3=32

[7]XXX(68t210)=96

[8]XXX68t=306

[9]XXXt=92

Substituting 92 into [1] in place of t
[10]XXX3s5(92)=30

[11]XXX3s=592302

[12]XXX3s=152

[13]XXXs=52