How do i solve 4x-y=-9 3x-3y=0 by elimination

First multiply the first equation by -3  , you get:-

-12x + 3y = 27
now add this to second equation
3x - 3y = 0

and you eliminate  y

solve for x and substitute this value of x into equation 1 to find y.

4x-y=-9, so y=4x+9
replace the y in the second equation iwth 4x+9:
3x-3(4x+9)=0
3x-12x-27=0
-9x=27
x=-3
y=4x+9=4*(-3)+9=-3

At a constant it will take one hour to travel 32 mi.at that speed it will take 1/2 hr to travel the remaining 16 mi.it will take 1+1/2 hr to travel the 48mi @ 32mph.so 1 hr = 60 min& 1/2 hr = 30 min1+1/2 hr = 90 min.there are 60s in each 90 × 60 = 3600 seconds.the real question seriously is he why are they driving so slow? ! lol.