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
It took lots of trial and error but i finally found out that 12% was added
Answer:
The answer is 28y + 63
Step-by-step explanation:
7(4y+9)
=28y+63