Question

Solve this 3x + 4y = 8 & 4.5x + 6y=12

Answer 1

3x+4y=8
4y=-3x+8
divide both sides by 4
y=-3/4x+2
plug y=-3/4x+2 in 3x+4y=8
 -> 4.5x+6(-3/4x+2)=12
4.5x-9/2x+12=12
decimal 9/2x=4.5x
4.5x-4.5x+12=12
x=0
plug x=0 in 3x+4y=8
4y=8
y=2

Answer 2

Multiply the first equality by 3/2 and you get the second

There are thus an infinite number of solutions : x can be any number and y=2-3x/4