Question

The two triangles are similar.

What is the value of x?

Answer 1

If two triangles are similar, their sides form a proportion.

`(3x+1)/(12)=(4x)/(12+3)\\\\(3x+1)/(12)=(4x)/(15)\qquad|\text{cross\ multiply}\\\\15(3x+1)=12(4x)\qquad|\text{use distributive property}\\\\(15)(3x)+(15)(1)=48x\\\\45x+15=48x\qquad|\text{subtract 45x from both sides}\\\\15=3x\qquad|\text{divide both sides by 3}\\\\5=x\to x=5`

Answer: x = 5

Answer 2

See picture reply. I hope this helps.