R=train speed
p=plaane speed
t=time
d=st
100=tr
350=pt
p=4r-20
ok so 100 times 3.5=350
times 1st equaton by 3.5
350=3.5tr
350=pt
sub
3.5tr=pt
divide both sides by t
3.5r=p
sub p=4r-20
3.5r=4r-20
minus 3.4 from both sides
0=0.5r-20
add 20
20=0.5r
times 2
40=r
sub
p=4r-20
p=4(40)-20
p=160-20
p=140
plane=140kmph
train=40kmph
4x + 160y = 120
and
1x + 240y = 80
that will be be the equations. if we multiply the bottom equation by 4 we get:
4x + 960y = 320
now subtract one equation from another:
4x + 160y = 120
-(4x + 960y = 320)
and get:
-800y = -200
y = $0.25
now plug this into one equation
x +240(.25) = 80
x + 60 = 80
x = $20
so $20 per day and $0.25 per mile
Answer:
-3p-4
Step-by-step explanation:
-(7p+6)-2(-1-2p)
-7p-6+2+4p
-7p+4p-6+2
-3p-6+2
-3p-4