Question 375628
r=-3s
r+4s=10

plug in -3s into r
so you get -3sr + 4s =10
add r's up and you get 1s=10
s=10

same for next problem
x-y=5
x+2y=7

isolate one of the variables
-y=5-x
divide by -
so you get y=-5+x
plug in for y
and solve


p l+l+w+w or 2l+2w
l= w+24
so plug in to ^^
2(w +24) +2w=268
so you get 
4w +48= 268
subtract by 48 and divide by 4
and you find w
plug in w into l+w+24
sorry but i didnt want to do them all if you really need help with them ill do it but next time try to do less