How do I find the gradiant of the following equations?

Question

4a+3b+27 The interections I get are when b =0 a= 6.75

when a = 0 b= 9

5a-2b= 28 The intercetions I get are when b = 0 a= 5.6

when a=0 b= -9

Answer 1

4a + 3b = 27

4a = -3b + 27

a = (-3/4)b + (27/4)

the slope of the line is -3/4.

Answer 2

Second is an equation. I am happy. But its not in x and y! what has it to do with slope? Do you have a and b axes or something?