The two triangular prisms shown below are similar. what is the value of x, the height of the larger prism?

Two solids are similar if their corresponding linear measurement units are proportional to each other. Scale factor is a/b, from the small prism, we get 8/10 or 4/5. 
Congruent ratios will mean similar solids or in this case, prisms.
Set-up a proportion to find x.
4/5 = 4.8/x
4x = 34
x= 6 cm.
The height of the larger prism is 6cm. 

Abit confused about what you mean, but i think you might be referring to slope intercept form: y = mx + bin that case b, or the y intercept is already given.(0,-1)find the slope by using the formulay2 - y1/x2 - x1the final slope will be 4/2, equivalent to 2.now your equation should look like thisy = 4/2x -1sorry if this didn’t you out!