SOLUTION: Please solve Using Substitution: {{{7s+5t=13}}} {{{3t-s=-13}}}

Algebra.Com
Question 243956: Please solve Using Substitution:


Answer by richwmiller(17219)   (Show Source): You can put this solution on YOUR website!
Please solve Using Substitution:
7s+5t=13
3t-s=-13
solve second for s
add 13 and s to both sides
3t+13=s
substitute s into first
7* (3t+13)+5t=13
21t+7*13+5t=13
combine
26t+7*13=13
divide by 13
2t+7=1
subtract 7 from both sides
2t=-6
t=-3
substitute t into second equation
why second?
it is easier to multiply and divide
3*(-3)-s=-13
-9-s=-13
multiply both sides by -1
9+S=13
s=4
and t=-3
check
7s+5t=13
7*4+5*(-3)=13
28-15=13
13=13
ok

RELATED QUESTIONS

5t+1>3t-13 (answered by Mathtut)
5t+1>3t-13 (answered by tvandenberg)
how do you solve... (answered by jim_thompson5910)
how to solve the expression: 4r + s + 7s + 3t +... (answered by Fombitz)
solve the inequality... (answered by Nate)
this did not come from a book but from a work sheet my teacher made R + S + T = 5 ;... (answered by stanbon)
Solve: 5t + 1 > 3t - 13 Is it: A.) t > -6 B.) t > -7 C.) t > 6 D.) t < 7... (answered by solver91311)
Please help me solve this equation tutor 3x+y+13 and 3x+2y=17 using... (answered by tutorcecilia)
Please help me. use the subtraction method to solve for s. 3t+5s=10 3t+ s=2 & (answered by ankor@dixie-net.com)