Answer:
5
Step-by-step explanation:
What we have to know is that when two triangles are similar their sides will always be proportional. So we will create a proportion that goes like this...[tex]\frac{\Delta1side}{\Delta1base} =\frac{\Delta2side}{\Delta2base}[/tex] but since it doesn't tell us the exact value of triangle 1. We will have to add 3 and 12 to get 15 which is the base of the first triangle. Now we're ready to write the proportion.
[tex]\frac{4x}{15}=\frac{3x+1}{12}[/tex]
Now we cross multiply and solve the equation...
[tex]48x=15(3x+1)\\48x=45x+15\\3x=15\\x=5[/tex]
So the value of x is 5.
