Solve the system of equations
4x+7y=47
5x-4y=-5

(3,5)

Step-by-step explanation:

To solve the system using the substitution method start by isolating one of the variables in the first equation.

4x+7y-7y=47 -7y

4x/ 4= (-7y+ 47)/4

x= -1.75y+ 11.75

Next, substitute x= -1.75y+ 11.75 into equation 2 replacing x.

5( -1.75y+ 11.75)-4y=-5

-8.75y+58.75 -4y=-5

-8.75y+58.75- 58.75 -4y=-5- 58.75

-8.75y-4y=-63.75

(-12.75y)/-12.75y =(-63.75)/-12.75y

y= 5

Last, substitute y=5 into equation 1 and solve.

4x+7(5)=47

4x+35-35=47-35

4x=12

x=3

distance covered by pamela in 9 l of fuel = 99km

let us apply unitary method here.

distance covered by pamela in 1 l of fuel =99/9 =11 km

now let us find distance covered by pamela if she has 12 l of fuel.

distance covered in 12 l = distance covered in 1 l of fuel * 12

we know that distance covered by here in 1 l is 11 km.

so distance covered in 12 l of fuel = 11*12 = 132 km.