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

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Answer 1 · 2015-10-21T04:00:44

#s=-2.5# #t=4.5#

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#