How do you solve these for s and t using the following equations?: 3s-5t=-30 and 7s+11t=32

1 Answer
Oct 21, 2015

s=-2.5 t=4.5

Explanation:

You first need to find the equation in terms of either s or t. I'm gonna do it in s.

So
=3s-5t=-30
=3s=-30+5t
=s=(-30+5t)/3 ------ (1)

7s+11t=32
7s=32-11t
s=(32-11t)/7 ------ (2)

Now equate the 2 terms of s

= (-30+5t)/3=(32-11t)/7

=7(-30+5t)=3(32-11t)

=-210+35t=96-33t

=-210-96=-35t-33t

=-306=-68t

=t=(-306)/-68

=t=4.5

Now swap the value of t in an original equation,

s=(-30+5(4.5))/3

s=-7.5/3

Therefore,

s=-2.5 t=4.5