2a - 3b = -11
a + 3b = 8

b = 3 and a = -1

Step-by-step explanation:

You have your given equation:

2a - 3b = -11

a + 3b = 8

You need to find what a and b is.

To find b:

2a - 3b = -11

-2a - 6b = -16

I multiplied a + 3b = 8 by -2. When you multiply a number you have to multiply all of them. You have to choose a number that would cancel out all of a.

So now your equation would look like this when you solve for b:

2a - 3b = -11

-2a - 6b = -16

a - 9 = -27 then you divide -9 to -27 which is 3 so b = 3.

To find a:

2a - 3b = -11

a + 3b = 8

I multiplied a + 3b = 8 by -1 and 2a - 3b = -11 by -1 as well.

Your equation will look like this when you solve for a:

-2a + 3b = 11

-1a - 3b = -8

-3a = 3 then divide -3 to 3 which is -1 so a = -1.

Check to see if you have the correct answer by plugging in the number you got for a and b into the equation and solve.

1. 2(-1) -3(3) = -11

 -2 - 9 = -11

2. -1 + 3(3) = 8

   -1 + 9 = 8

since the airplane is moving with constant speed then the distance travelled can be calculated by x=u*t

in km/h would be:

x=640*3.5=2.240 km

in m/s would be:

u=640 km/h= 640.000 m/h =640.000/ 3600 m/s =177.8 m/s

t= 3.5 h= 3.5 * 3600 s=12.600 s

then x=u*t= 177.8*12.600= 2.240.280 m