Solving using substitution and/or elimination method -5x+6y=-8 ; x-4y=24

Hmm
we can solve for xin second equation

add 4y both sides
x=24+4y
sub 24+4y for x in other equation

-5(24+4y)+6y=-8
-120-20y+6y=-8
-120-14y=-8
add 120 both sides
-14y=112
divide bot sides by -14
y=-8

sub back

x=24+4y
x=24+4(-8)
x=24-32
x=-8

answer is
(x,y)
(-8,-8)

    t = 7

Explanation:

If we replace every copy of x with t, then we go from this

F(x) = 3x+5

to this

F(t) = 3t + 5

All we've done really is change the letter. We still are dealing with a variable. We're told that F(t) is equal to 26, which would allow us to replace the "F(t)" with "26" in the second equation above.

So we now have the equation 26 = 3t+5 which is the same as 3t+5 = 26

Let's solve for t

3t+5 = 26

3t = 26-5 subtract 5 from both sides

3t = 21

t = 21/3 divide both sides by 3

t = 7  is the answer

Now note that...

F(t) = 3t + 5

F(7) = 3*7 + 5 replace t with 7

F(7) = 21 + 5

F(7) = 26

This means we got F(t) = 26 when t = 7

It's the same as saying x = 7 leads to F(x) = 26.

This helps confirm we have the correct answer.